Abstract: HTML5 is the latest standard of building Web applications. It introduces many new features to browsers, but also brings new security issues. The security of new features is the essence of HTML5 security. According to the differences in function, we analyze and summarize the security of new features including new label and form, communication, offline and storage, multimedia, performance, device access. The security problems and possible prevention methods are pointed out. Then we summarize existing researches, and classify HTML5 security problems into three categories: extending traditional threats, malicious use and improper use, to provide a new thought for the further study of HTML5 security. At last, four directions of the future work are pointed out: the security of new features, detection of malicious use, cross platform security and new security applications.