diff --git a/.changeset/sharp-lizards-learn.md b/.changeset/sharp-lizards-learn.md
new file mode 100644
index 00000000..586787dc
--- /dev/null
+++ b/.changeset/sharp-lizards-learn.md
@@ -0,0 +1,6 @@
+---
+'@pintora/cli': patch
+'@pintora/core': patch
+---
+
+eliminate config side effects of `render` function
diff --git a/packages/pintora-cli/src/__tests__/render.spec.ts b/packages/pintora-cli/src/__tests__/render.spec.ts
index 3be4da5c..789b042e 100644
--- a/packages/pintora-cli/src/__tests__/render.spec.ts
+++ b/packages/pintora-cli/src/__tests__/render.spec.ts
@@ -1,6 +1,7 @@
+import { pintoraStandalone } from '@pintora/standalone'
+import { EXAMPLES } from '@pintora/test-shared'
 import { SVG_MIME_TYPE } from '../const'
 import { render } from '../render'
-import { EXAMPLES } from '@pintora/test-shared'
 
 describe('render', () => {
   it('can output svg', async () => {
@@ -19,4 +20,22 @@ describe('render', () => {
     expect(buf.constructor).toBe(Buffer)
     expect(buf.length).toBeGreaterThan(0)
   })
+
+  it('pintoraConfig should not alter global config', async () => {
+    const oldTheme = pintoraStandalone.configApi.getConfig().themeConfig.theme
+    const oldUseMaxWidth = pintoraStandalone.configApi.getConfig().core?.useMaxWidth
+    await render({
+      code: EXAMPLES.er.code,
+      width: 1000,
+      pintoraConfig: {
+        themeConfig: {
+          theme: 'light',
+        },
+      },
+    })
+
+    const config = pintoraStandalone.configApi.getConfig()
+    expect(config.themeConfig.theme).toBe(oldTheme)
+    expect(config.core.useMaxWidth).toBe(oldUseMaxWidth)
+  })
 })
diff --git a/packages/pintora-cli/src/render.ts b/packages/pintora-cli/src/render.ts
index 6c75d85c..ce05a43d 100644
--- a/packages/pintora-cli/src/render.ts
+++ b/packages/pintora-cli/src/render.ts
@@ -41,15 +41,14 @@ function renderPrepare(opts: CLIRenderOptions) {
   return {
     container,
     pintorRender(renderOpts: Pick<RenderOptions, 'renderer'>) {
+      let config = pintoraStandalone.getConfig<PintoraConfig>()
       if (pintoraConfig) {
-        pintoraStandalone.setConfig(pintoraConfig)
+        config = pintoraStandalone.configApi.gnernateNewConfig(pintoraConfig)
       }
 
       const containerSize = opts.width ? { width: opts.width } : undefined
       if (opts.width) {
-        pintoraStandalone.setConfig({
-          core: { useMaxWidth: true },
-        })
+        config = pintoraStandalone.configApi.gnernateNewConfig({ core: { useMaxWidth: true } })
       }
 
       return new Promise<IRenderer>((resolve, reject) => {
@@ -59,7 +58,8 @@ function renderPrepare(opts: CLIRenderOptions) {
           containerSize,
           enhanceGraphicIR(ir) {
             if (!ir.bgColor) {
-              const themeVariables = pintoraStandalone.getConfig<PintoraConfig>().themeConfig.themeVariables
+              const themeVariables: Partial<PintoraConfig['themeConfig']['themeVariables']> =
+                config.themeConfig.themeVariables || {}
               const newBgColor =
                 backgroundColor ||
                 themeVariables.canvasBackground ||
@@ -81,6 +81,11 @@ function renderPrepare(opts: CLIRenderOptions) {
   }
 }
 
+/**
+ * Renders the Pintora CLI options to the specified output format.
+ * @param opts - The CLIRenderOptions.
+ * @returns A promise that resolves to the rendered output.
+ */
 export function render(opts: CLIRenderOptions) {
   const mimeType = opts.mimeType || 'image/png'
 
diff --git a/packages/pintora-core/src/config.ts b/packages/pintora-core/src/config.ts
index 50487e55..61b75b90 100644
--- a/packages/pintora-core/src/config.ts
+++ b/packages/pintora-core/src/config.ts
@@ -15,7 +15,7 @@ export interface PintoraConfig {
   themeConfig: {
     theme: string
     darkTheme?: string
-    themeVariables: ITheme
+    themeVariables?: ITheme
   }
 }
 
@@ -38,6 +38,9 @@ const configApi = {
   getConfig<T = PintoraConfig>() {
     return config as any as T
   },
+  /**
+   * Sets the configuration for Pintora.
+   */
   setConfig<T extends PintoraConfig = PintoraConfig>(c: DeepPartial<T>) {
     const newConfig = configApi.gnernateNewConfig(c)
     config = newConfig