With the development of mobile communication network and the popularity of smart phones, mobile phones are not just simple communication tools, but a protection tool which is used to authenticate the login or other sensitive operations for the Internet accounts. (mobile phone password protection). But on the other hand, mobile phone password protection is gradually facing with a series of security threats which possibly threaten the security of Internet accounts. Based on other researches and related cases, this paper is trying to take Tencent QQ, mobile banking and Alipay as the examples to analyze every security threat of mobile phone password protection in detail. It aims at enhancing the security consciousness of users and offering some solutions as well.