{

     "fontFamily": "微软雅黑",

     "fontSize": 12,

     "BaseSettings":{

         "font":1,

         "size":2

                    }

 }

 import json

 def loadFont():

     f = open("Settings.json", encoding='utf-8')  //设置以utf-8解码模式读取文件，encoding参数必须设置，否则默认以gbk模式读取文件，当文件中包含中文时，会报错

     setting = json.load(f)

     family = setting['BaseSettings']['size']   //注意多重结构的读取语法

     size = setting['fontSize']

     return family

 t = loadFont()

 print(t)

结果：
2