This paper presents a new encryption embedded processor aimed at the application requirement of wireless sensor network (WSN). The new encryption embedded processor not only offers Rivest Shamir Adlemen (RSA), Advanced Encryption Standard (AES), 3 Data Encryption Standard (3DES) and Secure Hash Algorithm 1 (SHA-1 ) security engines, but also involves a new memory encryption scheme. The new memory encryption scheme is implemented by a memory encryption cache (MEC), which protects the confidentiality of the memory by AES encryption. The experi- ments show that the new secure design only causes 1.9% additional delay on the critical path and cuts 25.7% power consumption when the processor writes data back. The new processor balances the performance overhead, the power consumption and the security and fully meets the wireless sen- sor environment requirement. After physical design, the new encryption embedded processor has been successfully tape-out.