In order to solve the problem of security gap in the transmission of mobile E-commerce information through WAP gateway, a double layer encryption schemes based on WAP is proposed, which combines with WAP security architecture and mobile E-commerce security architecture. The data is encrypted with the public key of application server on the mobile terminal firstly, and then the encrypted data is encrypted again with WTLS in the wireless network and TLS/SSL in wired networks, which realizes the double layer encryption transmission. The digital signature and verification based on elliptic curve cryptography are adopted in this system, which can fast verify the identity of both parties. The simulation and experiment are implemented based on OPNET system and C++. The simulation results shows this system has characteristics of high security, fast calculation speed, high channel utilization factor etc, which can meet the safety need of WAP mobile E-commerce.