Abstract: The problem which time randomization can' t defend differential power analysis completely and the defect of the MASK technique which is usually implemented for the power randomization is analyzed. Based on the absolutely resist differential power analysis, the design should focus on the resource and commonness, the paper propose a time and power randomization circuit, AES algorithm containing this circuit is implemented and is testified in the power collection and analysis system. The result of differential power analysis prove the design to be practical to resist DPA.