Abstract: In order to meet the design requirement of security chip with the functions of encryption and decryption under resource-constrained condition,this paper puts forward a light-weight AES encryption and decryption method.With 8-bit serial data path and modular composite structure,this method optimizes state matrix,mixcolumns module and key expansion module in the process of encryption and decryption.It is able to achieve the functions of encryption and decryption with minimal hardware resources and thus effectively improves the hardware utilization.According to simulation and experiment,the design has the advantages of small chip area and low power consumption,being available in wireless mobile network and other resource-constrained environments.