Abstract. As one of the basic technologies for building Internet of Things, wireless sensor networks (WSNs) are a hot research topic at present. In this paper, two basic structures of WSNs are described briefly, and the current security situation and security risks of WSNs are introduced. Then, this paper summarizes several mainstream ways of attacking identity authentication schemes that are applied to WSNs, including smart card theft, wireless sensor node capture, vampire attack and collusion attack, and presents some defensive measures. Finally, attacking principles of these attack methods are summarized, and some improvements are put forward.