Use Unicode internally, such as:

submit = SubmitField(u'登陆')

The template file must be saved in UTF-8 format encoding.

Add u in front of the string and pass in a unicode

Add this code before the python file

import sys
default_encoding = 'utf-8'
if sys.getdefaultencoding() != default_encoding:
    reload(sys)
    sys.setdefaultencoding(default_encoding)

That’s why I switched to python3

Suddenly I realized that what I wrote was a stupid method,

email=StringField('电子邮箱‘.decode('utf-8'),validators=[Required(),Length(1,64),Email()]) 
password=PasswordField('密码'.decode('utf-8'),validators=[Required()]) 
remember_me=BooleanField('记住我？'.decode('utf-8'))