您正在传递字符串； headers不能永远是JSON编码的字符串，它始终是Python字典.

You are passing in a string; headers can't ever be a JSON encoded string, it is always a Python dictionary.

print结果具有欺骗性； JSON编码的对象看起来很像Python字典表示形式，但是它们距离同一事物远.

The print results are deceptive; JSON encoded objects look a lot like Python dictionary representations but they are far from the same thing.

requests API 明确指出必须是字典:

The requests API clearly states that headers must be a dictionary:

• headers –(可选)与Request一起发送的HTTP标头字典.

• headers – (optional) Dictionary of HTTP Headers to send with the Request.

JSON数据是您要作为内容发送到另一台服务器的内容，而不是用于与Python API通信的内容.

JSON data is something you'd send as content to another server, not something you'd use to communicate with a Python API.