diff --git a/go.mod b/go.mod
index 272ce9d..85f7103 100644
--- a/go.mod
+++ b/go.mod
@@ -48,6 +48,7 @@ require (
 	github.com/ugorji/go/codec v1.3.1 // indirect
 	go.mongodb.org/mongo-driver/v2 v2.5.0 // indirect
 	golang.org/x/arch v0.22.0 // indirect
+	golang.org/x/image v0.43.0 // indirect
 	golang.org/x/net v0.55.0 // indirect
 	golang.org/x/sys v0.46.0 // indirect
 	golang.org/x/text v0.38.0 // indirect
diff --git a/go.sum b/go.sum
index 589dd17..bf300c4 100644
--- a/go.sum
+++ b/go.sum
@@ -111,6 +111,8 @@ golang.org/x/arch v0.22.0 h1:c/Zle32i5ttqRXjdLyyHZESLD/bB90DCU1g9l/0YBDI=
 golang.org/x/arch v0.22.0/go.mod h1:dNHoOeKiyja7GTvF9NJS1l3Z2yntpQNzgrjh1cU103A=
 golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
 golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
+golang.org/x/image v0.43.0 h1:FLxcP4ec2350nTfOC8ysKtqYSIFbk/QGjw1ZHNP4tsY=
+golang.org/x/image v0.43.0/go.mod h1:rrpelvGFt+kLPAjPM4HeWPgrl0FtafueU//e5N0qk/Q=
 golang.org/x/net v0.55.0 h1:bcvxaJn3e1U6InsFWt1JUq1aSjnRxLzT2rtD2KfkDF8=
 golang.org/x/net v0.55.0/go.mod h1:L5U2KuzuOe1lY7Z+aWVIKK6qEeJXnXV9yzGA+WCHJww=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/handlers/profile.go b/handlers/profile.go
index e314609..0d28654 100644
--- a/handlers/profile.go
+++ b/handlers/profile.go
@@ -1,7 +1,10 @@
 package handlers
 
 import (
+	"bytes"
 	"fmt"
+	"image"
+	"image/jpeg"
 	"io"
 	"net/http"
 	"os"
@@ -13,6 +16,9 @@ import (
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 
+	xdraw "golang.org/x/image/draw"
+	_ "golang.org/x/image/webp"
+
 	"go_blog/models"
 )
 
@@ -147,3 +153,92 @@ func UpdateProfile(db *gorm.DB, storagePath string) gin.HandlerFunc {
 		c.Redirect(http.StatusFound, "/profile?saved=1")
 	}
 }
+
+// UploadAvatar handles AJAX avatar upload with cropping.
+func UploadAvatar(db *gorm.DB, storagePath string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		session := sessions.Default(c)
+		userID := session.Get("user_id")
+
+		var user models.User
+		if err := db.First(&user, userID).Error; err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "User not found"})
+			return
+		}
+
+		file, header, err := c.Request.FormFile("avatar")
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "No file provided"})
+			return
+		}
+		defer file.Close()
+
+		// Validate extension.
+		ext := strings.ToLower(filepath.Ext(header.Filename))
+		if ext == "" || (ext != ".jpg" && ext != ".jpeg" && ext != ".png" && ext != ".gif" && ext != ".webp") {
+			ext = ".jpg"
+		}
+
+		// Read file bytes for image processing.
+		imgBytes, err := io.ReadAll(file)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to read file"})
+			return
+		}
+
+		// Decode, resize, and re-encode the image.
+		processedBytes, finalExt, err := processAvatar(imgBytes, ext)
+		if err != nil {
+			// Fall back to saving raw bytes if processing fails.
+			processedBytes = imgBytes
+			finalExt = ext
+		}
+
+		// Ensure avatar directory exists.
+		avatarDir := filepath.Join(storagePath, "avatars")
+		os.MkdirAll(avatarDir, 0755)
+
+		// Remove old avatar file.
+		if user.Avatar != "" {
+			oldPath := filepath.Join(avatarDir, user.Avatar)
+			os.Remove(oldPath)
+		}
+
+		// Save processed avatar.
+		savedName := fmt.Sprintf("%d%s", user.ID, finalExt)
+		savedPath := filepath.Join(avatarDir, savedName)
+		if err := os.WriteFile(savedPath, processedBytes, 0644); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to save avatar"})
+			return
+		}
+
+		// Update user record.
+		user.Avatar = savedName
+		db.Save(&user)
+
+		// Update session.
+		session.Set("avatar", savedName)
+		session.Save()
+
+		c.JSON(http.StatusOK, gin.H{"avatar": savedName})
+	}
+}
+
+// processAvatar decodes, resizes to 256x256, and re-encodes an avatar image as JPEG.
+func processAvatar(imgBytes []byte, ext string) ([]byte, string, error) {
+	src, _, err := image.Decode(bytes.NewReader(imgBytes))
+	if err != nil {
+		return nil, "", err
+	}
+
+	const targetSize = 256
+	dst := image.NewRGBA(image.Rect(0, 0, targetSize, targetSize))
+	xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, src.Bounds(), xdraw.Src, nil)
+
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, dst, &jpeg.Options{Quality: 85}); err != nil {
+		return nil, "", err
+	}
+
+	return buf.Bytes(), ".jpg", nil
+}
diff --git a/i18n/i18n.go b/i18n/i18n.go
index 9c1dd5b..6a82226 100644
--- a/i18n/i18n.go
+++ b/i18n/i18n.go
@@ -83,6 +83,14 @@ var translations = map[Lang]map[string]string{
 		"gender_male":            "Male",
 		"gender_female":          "Female",
 		"gender_other":           "Other",
+
+		// Avatar cropping
+		"crop_avatar_title": "Crop Avatar",
+		"crop_cancel":       "Cancel",
+		"crop_confirm":      "Confirm",
+		"crop_uploading":    "Uploading...",
+		"crop_success":      "Avatar updated.",
+		"crop_error":        "Failed to upload avatar. Please try again.",
 	},
 	ZH: {
 		// 导航
@@ -153,6 +161,14 @@ var translations = map[Lang]map[string]string{
 		"gender_male":            "男",
 		"gender_female":          "女",
 		"gender_other":           "其他",
+
+		// 头像裁剪
+		"crop_avatar_title": "裁剪头像",
+		"crop_cancel":       "取消",
+		"crop_confirm":      "确认",
+		"crop_uploading":    "上传中...",
+		"crop_success":      "头像已更新。",
+		"crop_error":        "头像上传失败，请重试。",
 	},
 }
 
diff --git a/main.go b/main.go
index f2e8383..e7ae4c4 100644
--- a/main.go
+++ b/main.go
@@ -64,6 +64,7 @@ func main() {
 	{
 		profile.GET("", handlers.ProfilePage(db))
 		profile.POST("", handlers.UpdateProfile(db, cfg.Path))
+		profile.POST("/avatar", handlers.UploadAvatar(db, cfg.Path))
 	}
 
 	// 9. Start the server.
diff --git a/templates/layouts/base.html b/templates/layouts/base.html
index f66e715..f0dd9b7 100644
--- a/templates/layouts/base.html
+++ b/templates/layouts/base.html
@@ -6,6 +6,8 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>{{.Title}} - {{index .Tr "site_title"}}</title>
     <script src="https://cdn.tailwindcss.com"></script>
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/cropperjs/1.6.2/cropper.min.css">
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/cropperjs/1.6.2/cropper.min.js"></script>
 </head>
 <body class="bg-gray-50 min-h-screen flex flex-col">
     <!-- Navigation -->
diff --git a/templates/pages/profile.html b/templates/pages/profile.html
index 2d7d834..0c9ab0c 100644
--- a/templates/pages/profile.html
+++ b/templates/pages/profile.html
@@ -15,24 +15,47 @@
     </div>
     {{end}}
 
+    <!-- Avatar Crop Modal -->
+    <div id="avatarCropModal" class="fixed inset-0 z-50 hidden items-center justify-center bg-black/50">
+        <div class="bg-white rounded-xl shadow-xl max-w-lg w-full mx-4 p-6">
+            <h3 class="text-lg font-semibold text-gray-800 mb-4">{{index .Tr "crop_avatar_title"}}</h3>
+            <div class="max-h-64 overflow-hidden mb-4 flex items-center justify-center bg-gray-100">
+                <img id="avatarCropImage" src="" alt="crop preview" class="max-w-full block">
+            </div>
+            <div class="flex gap-3 justify-end">
+                <button type="button" id="cropCancelBtn"
+                    class="px-4 py-2 rounded-lg border border-gray-300 text-gray-700 hover:bg-gray-100 transition-colors cursor-pointer">
+                    {{index .Tr "crop_cancel"}}
+                </button>
+                <button type="button" id="cropConfirmBtn"
+                    class="px-4 py-2 rounded-lg bg-blue-600 text-white hover:bg-blue-700 transition-colors cursor-pointer">
+                    {{index .Tr "crop_confirm"}}
+                </button>
+            </div>
+        </div>
+    </div>
+
     <form action="/profile" method="post" enctype="multipart/form-data" class="space-y-8">
         <!-- Avatar Section -->
         <div class="bg-white rounded-xl shadow-sm border border-gray-200 p-6">
             <h3 class="text-lg font-semibold text-gray-800 mb-4">{{index .Tr "profile_avatar"}}</h3>
             <div class="flex items-center gap-5">
-                <div class="w-20 h-20 rounded-full overflow-hidden border-2 border-gray-300 flex items-center justify-center bg-gray-200">
+                <div id="avatarPreviewContainer" class="w-20 h-20 rounded-full overflow-hidden border-2 border-gray-300 flex items-center justify-center bg-gray-200">
                     {{if .Profile.Avatar}}
-                        <img src="/uploads/avatars/{{.Profile.Avatar}}" alt="avatar" class="w-full h-full object-cover">
+                        <img id="avatarPreviewImg" src="/uploads/avatars/{{.Profile.Avatar}}" alt="avatar" class="w-full h-full object-cover">
                     {{else}}
-                        <svg class="w-10 h-10 text-gray-500" fill="currentColor" viewBox="0 0 24 24">
+                        <svg id="avatarPreviewSvg" class="w-10 h-10 text-gray-500" fill="currentColor" viewBox="0 0 24 24">
                             <path d="M12 12c2.7 0 4.8-2.1 4.8-4.8S14.7 2.4 12 2.4 7.2 4.5 7.2 7.2 9.3 12 12 12zm0 2.4c-3.2 0-9.6 1.6-9.6 4.8v1.2c0 .66.54 1.2 1.2 1.2h16.8c.66 0 1.2-.54 1.2-1.2v-1.2c0-3.2-6.4-4.8-9.6-4.8z"/>
                         </svg>
                     {{end}}
                 </div>
-                <label class="cursor-pointer bg-gray-200 text-gray-700 px-4 py-2 rounded-lg font-medium hover:bg-gray-300 transition-colors text-sm">
-                    {{index .Tr "profile_change_avatar"}}
-                    <input type="file" name="avatar" accept="image/*" class="hidden" onchange="this.form.submit()">
-                </label>
+                <div>
+                    <label class="cursor-pointer bg-gray-200 text-gray-700 px-4 py-2 rounded-lg font-medium hover:bg-gray-300 transition-colors text-sm">
+                        {{index .Tr "profile_change_avatar"}}
+                        <input type="file" id="avatarFileInput" name="avatar" accept="image/*" class="hidden">
+                    </label>
+                    <div id="avatarUploadStatus" class="mt-2 text-sm text-gray-500 hidden"></div>
+                </div>
             </div>
         </div>
 
@@ -96,4 +119,127 @@
 </section>
 
 {{template "footer" .}}
+
+<script>
+(function() {
+    var cropper = null;
+    var fileInput = document.getElementById('avatarFileInput');
+    var modal = document.getElementById('avatarCropModal');
+    var cropImage = document.getElementById('avatarCropImage');
+    var cancelBtn = document.getElementById('cropCancelBtn');
+    var confirmBtn = document.getElementById('cropConfirmBtn');
+    var statusDiv = document.getElementById('avatarUploadStatus');
+    var previewContainer = document.getElementById('avatarPreviewContainer');
+
+    // i18n strings from template
+    var i18nCropError = "{{index .Tr "crop_error"}}";
+    var i18nCropUploading = "{{index .Tr "crop_uploading"}}";
+    var i18nCropSuccess = "{{index .Tr "crop_success"}}";
+    var i18nCropConfirm = "{{index .Tr "crop_confirm"}}";
+
+    fileInput.addEventListener('change', function() {
+        var file = this.files[0];
+        if (!file) return;
+
+        if (!file.type.match(/^image\/(jpeg|png|gif|webp)$/)) {
+            showStatus(i18nCropError, 'red');
+            this.value = '';
+            return;
+        }
+
+        var reader = new FileReader();
+        reader.onload = function(e) {
+            cropImage.src = e.target.result;
+            modal.classList.remove('hidden');
+            modal.classList.add('flex');
+
+            if (cropper) cropper.destroy();
+            cropper = new Cropper(cropImage, {
+                aspectRatio: 1,
+                viewMode: 1,
+                autoCropArea: 0.85,
+                responsive: true
+            });
+        };
+        reader.readAsDataURL(file);
+    });
+
+    cancelBtn.addEventListener('click', function() {
+        if (cropper) { cropper.destroy(); cropper = null; }
+        modal.classList.add('hidden');
+        modal.classList.remove('flex');
+        fileInput.value = '';
+    });
+
+    confirmBtn.addEventListener('click', function() {
+        if (!cropper) return;
+
+        confirmBtn.disabled = true;
+        confirmBtn.textContent = i18nCropUploading;
+        showStatus(i18nCropUploading, 'gray');
+
+        var canvas = cropper.getCroppedCanvas({
+            width: 256,
+            height: 256,
+            maxWidth: 512,
+            maxHeight: 512,
+            imageSmoothingEnabled: true,
+            imageSmoothingQuality: 'high'
+        });
+
+        canvas.toBlob(function(blob) {
+            var formData = new FormData();
+            formData.append('avatar', blob, 'avatar.jpg');
+
+            fetch('/profile/avatar', {
+                method: 'POST',
+                body: formData,
+                credentials: 'same-origin'
+            })
+            .then(function(res) { return res.json(); })
+            .then(function(data) {
+                if (data.avatar) {
+                    var ts = Date.now();
+                    var avatarUrl = '/uploads/avatars/' + data.avatar + '?t=' + ts;
+
+                    // Update profile page preview
+                    previewContainer.innerHTML =
+                        '<img src="' + avatarUrl + '" alt="avatar" class="w-full h-full object-cover">';
+
+                    // Update nav bar avatar
+                    var navAvatarBtn = document.getElementById('avatarBtn');
+                    if (navAvatarBtn) {
+                        navAvatarBtn.innerHTML =
+                            '<img src="' + avatarUrl + '" alt="avatar" class="w-full h-full object-cover">';
+                    }
+
+                    showStatus(i18nCropSuccess, 'green');
+                } else {
+                    showStatus(data.error || i18nCropError, 'red');
+                }
+            })
+            .catch(function() {
+                showStatus(i18nCropError, 'red');
+            })
+            .finally(function() {
+                if (cropper) { cropper.destroy(); cropper = null; }
+                modal.classList.add('hidden');
+                modal.classList.remove('flex');
+                fileInput.value = '';
+                confirmBtn.disabled = false;
+                confirmBtn.textContent = i18nCropConfirm;
+            });
+        }, 'image/jpeg', 0.92);
+    });
+
+    function showStatus(msg, color) {
+        statusDiv.textContent = msg;
+        statusDiv.classList.remove('hidden', 'text-gray-500', 'text-green-600', 'text-red-600');
+        if (color === 'green') statusDiv.classList.add('text-green-600');
+        else if (color === 'red') statusDiv.classList.add('text-red-600');
+        else statusDiv.classList.add('text-gray-500');
+    }
+})();
+</script>
+
 {{end}}