diff --git a/server.js b/server.js
index 3cd6ac7..027328e 100644
--- a/server.js
+++ b/server.js
@@ -694,7 +694,7 @@ function generateTableImage(params) {
     const headerHeight = fontSize * 2.5;
     const rowHeight = fontSize * 2.2;
     const titleHeight = title ? fontSize * 3 : 0;
-    const tableHeight = headerHeight + rows.length * rowHeight + borderWidth * 2;
+    const tableHeight = headerHeight + rows.length * rowHeight;
     const finalHeight = tableHeight + titleHeight;
 
     // 创建正式 canvas
@@ -763,8 +763,9 @@ function generateTableImage(params) {
     ctx.strokeStyle = themeConfig.borderColor;
     ctx.lineWidth = borderWidth;
 
-    // 外边框
-    ctx.strokeRect(0, startY, finalWidth, tableHeight);
+    // 外边框（向内偏移半个线宽，确保边框完全在画布内）
+    const offset = borderWidth / 2;
+    ctx.strokeRect(offset, startY + offset, finalWidth - borderWidth, tableHeight - borderWidth);
 
     // 横线
     ctx.beginPath();