diff --git a/src/whiteboard/shape-paths.ts b/src/whiteboard/shape-paths.ts
index 03c557f..cbb4817 100644
--- a/src/whiteboard/shape-paths.ts
+++ b/src/whiteboard/shape-paths.ts
@@ -1,5 +1,5 @@
 import type { WNode } from './types.js';
-import { BORDER_WIDTH_MAP, r } from './utils.js';
+import { BORDER_WIDTH_MAP, r, withoutStrokeAttrs } from './utils.js';
 
 // ─── Shape Path Registry ────────────────────────────────────────────────────
 
@@ -87,9 +87,12 @@ registerShapePath(['trapezoid', 'flow_chart_trapezoid'], (w, h, sa) => {
 
 registerShapePath(['cylinder', 'flow_chart_cylinder', 'data_base'], (w, h, sa, n) => {
   const ry = h * 0.1;
+  // 圆柱体侧面用 line 描边，中间矩形不能再继承 sa 里的 stroke，
+  // 否则会出现 stroke="..." stroke="none" 的非法重复属性。
+  const bodySa = withoutStrokeAttrs(sa);
   return [
     `<ellipse cx="${w / 2}" cy="${ry}" rx="${w / 2}" ry="${ry}" ${sa}/>`,
-    `<rect x="0" y="${ry}" width="${w}" height="${h - 2 * ry}" ${sa} stroke="none"/>`,
+    `<rect x="0" y="${ry}" width="${w}" height="${h - 2 * ry}" ${bodySa} stroke="none"/>`,
     `<line x1="0" y1="${ry}" x2="0" y2="${h - ry}" stroke="${n.style?.border_color ?? '#333'}" stroke-width="${BORDER_WIDTH_MAP[n.style?.border_width ?? 'narrow'] ?? 1}"/>`,
     `<line x1="${w}" y1="${ry}" x2="${w}" y2="${h - ry}" stroke="${n.style?.border_color ?? '#333'}" stroke-width="${BORDER_WIDTH_MAP[n.style?.border_width ?? 'narrow'] ?? 1}"/>`,
     `<ellipse cx="${w / 2}" cy="${h - ry}" rx="${w / 2}" ry="${ry}" ${sa}/>`,
diff --git a/src/whiteboard/utils.ts b/src/whiteboard/utils.ts
index 03c0fae..9e7e97d 100644
--- a/src/whiteboard/utils.ts
+++ b/src/whiteboard/utils.ts
@@ -179,6 +179,14 @@ export function styleAttrs (s?: WStyle): string {
   return parts.join(' ');
 }
 
+/** 从 styleAttrs 结果中剥离 stroke 相关属性，便于再单独指定 stroke */
+export function withoutStrokeAttrs (sa: string): string {
+  return sa
+    .replace(/\bstroke(?:-width|-opacity|-dasharray)?="[^"]*"/g, '')
+    .replace(/\s+/g, ' ')
+    .trim();
+}
+
 export function transformAttr (n: WNode): string {
   const parts: string[] = [];
   if (n.x != null || n.y != null) parts.push(`translate(${r(n.x ?? 0)},${r(n.y ?? 0)})`);
diff --git a/tests/whiteboard/shape-paths.test.ts b/tests/whiteboard/shape-paths.test.ts
index d63fa6a..96d1dee 100644
--- a/tests/whiteboard/shape-paths.test.ts
+++ b/tests/whiteboard/shape-paths.test.ts
@@ -83,6 +83,18 @@ describe('shape-paths: composite shapes with multiple elements', () => {
     expect(out).toContain('stroke="#444"');
   });
 
+  it('cylinder body rect does not redefine stroke attribute', () => {
+    const fn = getShapePath('cylinder')!;
+    const sa = 'fill="#dff5e5" stroke="#000000" stroke-width="2"';
+    const out = fn(100, 80, sa, blankNode({ style: { border_color: '#000000' } as any }));
+    const body = out.split('\n').find((line) => line.includes('<rect'))!;
+    // 每个属性名只能出现一次，避免浏览器报 Attribute stroke redefined
+    expect(body).toMatch(/stroke="none"/);
+    expect(body.match(/\bstroke="/g)?.length).toBe(1);
+    expect(body).not.toMatch(/stroke-width=/);
+    expect(body).toContain('fill="#dff5e5"');
+  });
+
   it('cylinder uses default stroke when border_color missing', () => {
     const fn = getShapePath('cylinder')!;
     const out = fn(100, 80, SA, blankNode());
diff --git a/tests/whiteboard/utils.test.ts b/tests/whiteboard/utils.test.ts
index b1f5623..90eb9a2 100644
--- a/tests/whiteboard/utils.test.ts
+++ b/tests/whiteboard/utils.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from 'vitest';
 import {
-  r, esc, styleAttrs, transformAttr, walkNodes, filterNodes, gWrap, nodeDataAttrs,
+  r, esc, styleAttrs, withoutStrokeAttrs, transformAttr, walkNodes, filterNodes, gWrap, nodeDataAttrs,
   BORDER_WIDTH_MAP, DASH_ARRAY_MAP,
 } from '../../src/whiteboard/utils.js';
 
@@ -78,6 +78,21 @@ describe('styleAttrs', () => {
   });
 });
 
+describe('withoutStrokeAttrs', () => {
+  it('strips stroke and related attributes while keeping fill', () => {
+    expect(withoutStrokeAttrs('fill="#eee" stroke="#333"')).toBe('fill="#eee"');
+    expect(
+      withoutStrokeAttrs('fill="#dff5e5" stroke="#000" stroke-width="2" stroke-dasharray="8,4"'),
+    ).toBe('fill="#dff5e5"');
+  });
+
+  it('keeps fill-opacity', () => {
+    expect(withoutStrokeAttrs('fill="#f00" fill-opacity="0.5" stroke="#333"')).toBe(
+      'fill="#f00" fill-opacity="0.5"',
+    );
+  });
+});
+
 // ─── transformAttr ──────────────────────────────────────────────────────────
 
 describe('transformAttr', () => {