diff --git a/Dockerfile b/Dockerfile
index f8a131b..fffb906 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,7 +6,11 @@ ENV PYTHONUNBUFFERED=1 \
     PIP_DISABLE_PIP_VERSION_CHECK=1
 WORKDIR /app
 COPY requirements.txt ./
-RUN apt-get update && apt-get install -y --no-install-recommends ffmpeg \
+ARG DEBIAN_MIRROR=https://deb.debian.org
+RUN case "$DEBIAN_MIRROR" in https://deb.debian.org|https://mirrors.tuna.tsinghua.edu.cn) ;; *) exit 2;; esac \
+    && sed -i "s|http://deb.debian.org|$DEBIAN_MIRROR|g" /etc/apt/sources.list.d/debian.sources \
+    && apt-get -o Acquire::Retries=2 -o Acquire::https::Timeout=30 update \
+    && apt-get -o Acquire::Retries=2 -o Acquire::https::Timeout=30 install -y --no-install-recommends ffmpeg \
     && rm -rf /var/lib/apt/lists/*
 RUN python -m pip install --no-cache-dir -r requirements.txt \
     && groupadd --gid 10001 baiyue \
diff --git a/Jenkinsfile b/Jenkinsfile
index 719fda9..01080ee 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -23,6 +23,9 @@ pipeline {
           if (!((params.ASR_PROVIDER ?: '') in ['', 'baidu'])) {
             error('Gray speech provider must be baidu or disabled')
           }
+          if (!((params.DEBIAN_MIRROR ?: 'https://deb.debian.org') in ['https://deb.debian.org', 'https://mirrors.tuna.tsinghua.edu.cn'])) {
+            error('Select a supported Debian mirror')
+          }
         }
         sh '''set -eu
           for file in deploy/*.sh; do bash -n "$file"; done
@@ -32,12 +35,12 @@ pipeline {
     }
     stage('Build and test image') {
       steps {
-        withEnv(["PYTHON_BASE_IMAGE=${params.PYTHON_BASE_IMAGE}"]) {
+        withEnv(["PYTHON_BASE_IMAGE=${params.PYTHON_BASE_IMAGE}", "DEBIAN_MIRROR=${params.DEBIAN_MIRROR ?: 'https://deb.debian.org'}"]) {
           sh '''set -eu
-            docker build --target test --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" -t "$CHAT_IMAGE-test" .
-            docker build --target production --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" \
+            docker build --target test --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" --build-arg DEBIAN_MIRROR="$DEBIAN_MIRROR" -t "$CHAT_IMAGE-test" .
+            docker build --target production --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" --build-arg DEBIAN_MIRROR="$DEBIAN_MIRROR" \
               --label "org.opencontainers.image.revision=$SOURCE_COMMIT" -t "$CHAT_IMAGE" .
-            docker build --target certbot --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" \
+            docker build --target certbot --build-arg PYTHON_BASE_IMAGE="$PYTHON_BASE_IMAGE" --build-arg DEBIAN_MIRROR="$DEBIAN_MIRROR" \
               --label "org.opencontainers.image.revision=$SOURCE_COMMIT" -t "$CERTBOT_IMAGE" .
           '''
         }
diff --git a/docs/deployment.md b/docs/deployment.md
index c6234be..b225624 100644
--- a/docs/deployment.md
+++ b/docs/deployment.md
@@ -19,6 +19,7 @@
 | `ENVIRONMENT` | 单选 `gray`，流水线拒绝其他值 |
 | `SOURCE_REF` | 本次发布的不可变标签或提交，也可明确选择开发分支 |
 | `PYTHON_BASE_IMAGE` | 已验证的官方 Python 3.12 基础镜像 |
+| `DEBIAN_MIRROR` | 默认 `https://deb.debian.org`；国内可选 `https://mirrors.tuna.tsinghua.edu.cn`，保留 Debian 签名校验 |
 | `PUBLIC_ORIGIN` | 独立 HTTPS 域名，不带子路径 |
 | `HOST_PORT` | 已确认空闲的宿主机回环端口，如 `29013` |
 | `GRAY_DEPLOY_DIR` | 专用目录，末级必须为 `gray-logistics-chat` |