Based on the analysis of security threats faced by the WSN, typical factors which affect the security of WSN are analyzed by building a simulation environment of WSN, then the security status of WSN is analyzed in different variations of network security threats and attacks. For each of the security evaluation index of WSN, this paper studies the corresponding security evaluation methods. By using WSN security evaluation methods, the WSN security evaluation experiements are carried out, that is the security evaluation index of WSN are carried out. Thus the risk of WSN is reduced from source, and the security of WSN is ensured.