diff --git a/third_party_demo/init.bash b/third_party_demo/init.bash
new file mode 100644
index 0000000..1d4763d
--- /dev/null
+++ b/third_party_demo/init.bash
@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+set -euo pipefail
+root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$root"
+origin="$(git remote get-url origin)"
+origin="${origin%/}"
+remote_root="$(printf '%s\n' "$origin" | sed -E 's#/[^/]+(\.git)?$##')"
+fetch_repo() {
+  local repo="$1"
+  local branch="$2"
+  local dir="$3"
+  if [ -e "$dir" ]; then
+    printf '路径【%s】已存在，跳过初始化\n' "$dir"
+    return 0
+  fi
+  git clone --branch "$branch" --single-branch "$repo" "$dir"
+}
+fetch_repo_ex() {
+  local name="$1"
+  local repo="${remote_root}/${name}"
+  local branch="master"
+  fetch_repo "$repo" "$branch" "third_party/${name}"
+}
+clone_git_shallow() {
+  if [ "$#" -ne 2 ]; then
+    printf '用法: clone_git_shallow <git地址> <分支或标签>\n' >&2
+    return 2
+  fi
+  local git_url="${1%/}"
+  local branch="$2"
+  local repo_name="${git_url##*/}"
+  local dir
+  repo_name="${repo_name%.git}"
+  dir="third_party/${repo_name}"
+  if [ -e "$dir" ]; then
+    printf '路径【%s】已存在，跳过初始化\n' "$dir"
+    return 0
+  fi
+  git clone --branch "$branch" --depth 1 --single-branch "$git_url" "$dir"
+}
+
+mkdir -p third_party
+clone_git_shallow "https://github.com/nlohmann/json.git" "v3.12.0"
+fetch_repo_ex "CPP_Core"