The stability problem of dynamic stability of power system has a challenge in modern power system engineering. Synchronous generator excitation control is one of the most important measures to improve power system stability and to guarantee the quality of electrical power it provides. In a synchronous generator, the electrometrical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a damper system. Therefore, we consider the problem of enhancing the stability of PID controlled automatic voltage regulator based on differential evolution mechanism optimization. Firstly, the multi-mutation strategies and worst one elimination system are integrated into differential evolution algorithm. Then parameters of PID are self-adjusted by using improved differential evolution mechanism, so as to realize self-tuning of automatic voltage regulator. The simulation results show that the proposed method can get better dynamic respond behavior than other conventional methods.