diff --git a/miniapp/pages/index/index.js b/miniapp/pages/index/index.js
index 34a6d2e..689d992 100644
--- a/miniapp/pages/index/index.js
+++ b/miniapp/pages/index/index.js
@@ -401,6 +401,8 @@ function buildSankeyLayout(links, width, height, renderOptions) {
   const sourceGapCount = Math.max(0, sourceNames.length - 1);
   const sourceContentHeight = Math.max(10, height - padding * 2 - sourceGapCount * nodeGap);
   const sourceUnitHeight = sourceContentHeight / totalValue;
+  const sourceTotalNodeHeight = totalValue * sourceUnitHeight;
+  const sourceSpanHeight = sourceTotalNodeHeight + sourceGapCount * nodeGap;
 
   const sourcePos = {};
   let sourceCursorY = padding;
@@ -414,13 +416,19 @@ function buildSankeyLayout(links, width, height, renderOptions) {
   const targetTotalValue = targetNames.reduce((sum, name) => sum + targetValueMap[name], 0);
   const targetUnitHeight = targetTotalValue > 0 ? sourceUnitHeight : 0;
   const targetTotalNodeHeight = targetTotalValue * targetUnitHeight;
-  const targetBlockHeight = targetTotalNodeHeight + targetGapCount * nodeGap;
-  const layoutHeight = Math.max(10, height - padding * 2);
+  let targetGap = nodeGap;
+  if (targetAlignMode === 'between' && targetNames.length > 1) {
+    // 与 Web 端一致：两端对齐时，目标列整体高度与 source 列跨度一致。
+    targetGap = (sourceSpanHeight - targetTotalNodeHeight) / (targetNames.length - 1);
+  }
+  targetGap = Math.max(0, targetGap);
+
+  const targetBlockHeight = targetTotalNodeHeight + targetGapCount * targetGap;
   let targetStartY = padding;
   if (targetAlignMode === 'middle') {
-    targetStartY = padding + Math.max(0, (layoutHeight - targetBlockHeight) / 2);
+    targetStartY = padding + Math.max(0, (sourceSpanHeight - targetBlockHeight) / 2);
   } else if (targetAlignMode === 'bottom') {
-    targetStartY = padding + Math.max(0, layoutHeight - targetBlockHeight);
+    targetStartY = padding + Math.max(0, sourceSpanHeight - targetBlockHeight);
   } else if (targetAlignMode === 'top') {
     targetStartY = padding;
   }
@@ -430,7 +438,7 @@ function buildSankeyLayout(links, width, height, renderOptions) {
   targetNames.forEach((name) => {
     const nodeHeight = Math.max(2, targetValueMap[name] * targetUnitHeight);
     targetPos[name] = { y: targetCursorY, h: nodeHeight };
-    targetCursorY += nodeHeight + nodeGap;
+    targetCursorY += nodeHeight + targetGap;
   });
 
   const sourceOffset = {};