Wireless application protocol (WAP)is a set of protocol designed for mobile terminal toconnect to Inteet and is likely to become world stan-dard. Wireless transport layer security (WTLS) incor-porates the security features in WAP. In this paper,the analysis of the performance of WTLS is made.Two improvement schemes on WTLS are given: oneis that the client stores the certificate of servers; theother is that a new WTLS protocol is proposed basedon the designed authentication scheme.