Bitbucket提供了REST API，可以使用该API来创建和管理Pull Request。下面是一个使用Python语言和Bitbucket REST API创建Pull Request的示例代码：

import requests
import json

# 定义Bitbucket的API基本信息
base_url = 'https://api.bitbucket.org/2.0'
username = 'your_username'
password = 'your_password'
repository_owner = 'repository_owner'
repository_name = 'repository_name'

# 定义源存储库和目标存储库
source_repository = {
  "full_name": "{}/{}".format(repository_owner, repository_name),
  "branch": {
    "name": "feature_branch"
  }
}
destination_repository = {
  "full_name": "{}/{}".format(repository_owner, repository_name),
  "branch": {
    "name": "master"
  }
}

# 创建Pull Request的标题和描述
title = "My Pull Request"
description = "This is a Pull Request created using Bitbucket API."

# 创建Pull Request的请求体
pull_request_payload = {
  "title": title,
  "description": description,
  "source": source_repository,
  "destination": destination_repository
}

# 发送POST请求创建Pull Request
response = requests.post(
  '{}/repositories/{}/{}/pullrequests'.format(base_url, repository_owner, repository_name),
  auth=(username, password),
  json=pull_request_payload
)

# 打印创建结果
if response.status_code == 201:
  print("Pull Request created successfully.")
else:
  print("Failed to create Pull Request. Reason: {}".format(response.text))

请将上述代码中的your_username、your_password、repository_owner和repository_name替换为你自己的Bitbucket账户信息和存储库信息。同时，根据你的实际情况修改source_repository和destination_repository的分支名称。

这个示例代码将创建一个从source_repository的feature_branch分支到destination_repository的master分支的Pull Request，并设置了标题和描述。