参考问题
参考资料
最终代码:

 1def safe_clean(text):
 2    from flask import Markup
 3    from bleach import clean
 4    tags = ['b','i','font','br']
 5    attrs = {
 6        '*':['style'],
 7        'font':['color']
 8    }
 9    styles = ['color']
10    return Markup(clean(text,tags = tags,
11                        attributes = attrs,
12                        styles = styles))

自定义filter过滤器