diff --git a/models/policy.go b/models/policy.go
index fc9708425b8ba88ea523c8e58e11ff88bb068212..2aa248f70b3542ee3093eb0eda88cc13c871937a 100644
--- a/models/policy.go
+++ b/models/policy.go
@@ -54,7 +54,7 @@ var thumbSuffix = map[string][]string{
 	"local":    {},
 	"qiniu":    {".psd", ".jpg", ".jpeg", ".png", ".gif", ".webp", ".tiff", ".bmp"},
 	"oss":      {".jpg", ".jpeg", ".png", ".gif", ".webp", ".tiff", ".bmp"},
-	"cos":      {},
+	"cos":      {".jpg", ".jpeg", ".png", ".gif", ".webp", ".tiff", ".bmp"},
 	"upyun":    {".svg", ".jpg", ".jpeg", ".png", ".gif", ".webp", ".tiff", ".bmp"},
 	"remote":   {},
 	"onedrive": {"*"},
diff --git a/pkg/filesystem/driver/cos/handler.go b/pkg/filesystem/driver/cos/handler.go
index f012350dc8625cae3f71c81c7e399cb603278f01..0190d9816850191e2c6686aeef741e2fdc8e2d6c 100644
--- a/pkg/filesystem/driver/cos/handler.go
+++ b/pkg/filesystem/driver/cos/handler.go
@@ -143,7 +143,34 @@ func (handler Driver) Delete(ctx context.Context, files []string) ([]string, err
 
 // Thumb 获取文件缩略图
 func (handler Driver) Thumb(ctx context.Context, path string) (*response.ContentResponse, error) {
-	return nil, errors.New("未实现")
+	var (
+		thumbSize = [2]uint{400, 300}
+		ok        = false
+	)
+	if thumbSize, ok = ctx.Value(fsctx.ThumbSizeCtx).([2]uint); !ok {
+		return nil, errors.New("无法获取缩略图尺寸设置")
+	}
+	thumbParam := fmt.Sprintf("imageMogr2/thumbnail/%dx%d", thumbSize[0], thumbSize[1])
+
+	source, err := handler.signSourceURL(
+		ctx,
+		path,
+		int64(model.GetIntSetting("preview_timeout", 60)),
+		&urlOption{},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	thumbURL, _ := url.Parse(source)
+	thumbQuery := thumbURL.Query()
+	thumbQuery.Add(thumbParam, "")
+	thumbURL.RawQuery = thumbQuery.Encode()
+
+	return &response.ContentResponse{
+		Redirect: true,
+		URL:      thumbURL.String(),
+	}, nil
 }
 
 // Source 获取外链URL