解決辦法：

修改url為手機版的地址：http://fanyi.baidu.com/basetrans
User-Agent也用手機版的

測試代碼：

# -*- coding: utf-8 -*-
"""
-------------------------------------------------
   File Name：     requestsGet
   Description :    爬取在線翻譯數據s
   Author :       神秘藏寶室
   date：          2018-04-17
-------------------------------------------------
   Change Activity:
                   2018-04-17:
-------------------------------------------------
"""
import requests
url = "http://fanyi.baidu.com/basetrans"

data = {
    "query":"你好世界",
    "from":"zh",
    "to":"en",

}

headers = {
    "User-Agent":"Mozilla/5.0 (Linux; Android 5.1.1; Nexus 6 Build/LYZ28E) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Mobile Safari/537.36",
        }

response = requests.post(url,data = data,headers = headers)

# print response.request.url     #請求地址
# print response.url              #響應地址
# print response.request.headers  #請求頭
# print response.headers          #響應頭
print response.content.decode(‘unicode-escape‘)     #顯示出來unicode的中文
# print response.text
 

返回結果：

{"errno":0,"from":"zh","to":"en","trans":[{"dst":"Hello world","prefixWrap":0,"src":"你好世界","relation":[],"result":[[0,"Hello world",["0|12"],[],["0|12"],["0|11"]]]}],"dict":[],"keywords":[{"means":["hello","hi","How do you do!"],"word":"你好"}]}

python爬取百度翻譯返回：{'error': 997, 'from': 'zh', 'to': 'en', 'query 問題