diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2a7c6b7ffd5..025305b34ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -46,6 +46,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Sandbox/Docker setup command parsing: accept `agents.*.sandbox.docker.setupCommand` as either a string or a string array, and normalize arrays to newline-delimited shell scripts so multi-step setup commands no longer concatenate without separators. (#31953) Thanks @liuxiaopai-ai.
 - Security/Node exec approvals: preserve shell/dispatch-wrapper argv semantics during approval hardening so approved wrapper commands (for example `env sh -c ...`) cannot drift into a different runtime command shape, and add regression coverage for both approval-plan generation and approved runtime execution paths. Thanks @tdjackey for reporting.
 - Sandbox/Bootstrap context boundary hardening: reject symlink/hardlink alias bootstrap seed files that resolve outside the source workspace and switch post-compaction `AGENTS.md` context reads to boundary-verified file opens, preventing host file content from being injected via workspace aliasing. Thanks @tdjackey for reporting.
 - Browser/Security output boundary hardening: replace check-then-rename output commits with root-bound fd-verified writes, unify install/skills canonical path-boundary checks, and add regression coverage for symlink-rebind race paths across browser output and shared fs-safe write flows. Thanks @tdjackey for reporting.
diff --git a/src/config/config.sandbox-docker.test.ts b/src/config/config.sandbox-docker.test.ts
index 138a254411d..56d041b180d 100644
--- a/src/config/config.sandbox-docker.test.ts
+++ b/src/config/config.sandbox-docker.test.ts
@@ -7,6 +7,26 @@ import {
 import { validateConfigObject } from "./config.js";
 
 describe("sandbox docker config", () => {
+  it("joins setupCommand arrays with newlines", () => {
+    const res = validateConfigObject({
+      agents: {
+        defaults: {
+          sandbox: {
+            docker: {
+              setupCommand: ["apt-get update", "apt-get install -y curl"],
+            },
+          },
+        },
+      },
+    });
+    expect(res.ok).toBe(true);
+    if (res.ok) {
+      expect(res.config.agents?.defaults?.sandbox?.docker?.setupCommand).toBe(
+        "apt-get update\napt-get install -y curl",
+      );
+    }
+  });
+
   it("accepts safe binds array in sandbox.docker config", () => {
     const res = validateConfigObject({
       agents: {
diff --git a/src/config/types.sandbox.ts b/src/config/types.sandbox.ts
index b4d5e6e2027..047f10cde53 100644
--- a/src/config/types.sandbox.ts
+++ b/src/config/types.sandbox.ts
@@ -17,7 +17,7 @@ export type SandboxDockerSettings = {
   capDrop?: string[];
   /** Extra environment variables for sandbox exec. */
   env?: Record<string, string>;
-  /** Optional setup command run once after container creation. */
+  /** Optional setup command run once after container creation (array entries are joined by newline). */
   setupCommand?: string;
   /** Limit container PIDs (0 = Docker default). */
   pidsLimit?: number;
diff --git a/src/config/zod-schema.agent-runtime.ts b/src/config/zod-schema.agent-runtime.ts
index 63bec45b0ac..3f1ddb61e71 100644
--- a/src/config/zod-schema.agent-runtime.ts
+++ b/src/config/zod-schema.agent-runtime.ts
@@ -102,7 +102,10 @@ export const SandboxDockerSchema = z
     user: z.string().optional(),
     capDrop: z.array(z.string()).optional(),
     env: z.record(z.string(), z.string()).optional(),
-    setupCommand: z.string().optional(),
+    setupCommand: z
+      .union([z.string(), z.array(z.string())])
+      .transform((value) => (Array.isArray(value) ? value.join("\n") : value))
+      .optional(),
     pidsLimit: z.number().int().positive().optional(),
     memory: z.union([z.string(), z.number()]).optional(),
     memorySwap: z.union([z.string(), z.number()]).optional(),