import base64
def get_basic_auth_str(username, password):
  temp_str = username + ':' + password
  # 转成bytes string
  bytesString = temp_str.encode(encoding="utf-8")
  # base64 编码
  encodestr = base64.b64encode(bytesString)
  # 解码
  decodestr = base64.b64decode(encodestr)

  return 'Basic ' + encodestr.decode()

print(get_basic_auth_str('admin', '123456'))

Basic YWRtaW46MTIzNDU2