In order to improce the dynamic and ststic performamces of the excitation control system and enhamce the ability of restraining disturbance,unadvisablc it is to use still the traditional PID controller for meeting the requirement,so new algorithms should be introdyced.The fractional order PID controller was proposed,in which two parameters more than the traditional PID controller can be regulated.The scope of controlling can be adjusted more widely and the controller can well meet the needs of the current excitation control system.The performance of the controller proposed was compared with that of the PID controller by simulations,The results show that the fractional order PID controller is superior to the traditional one.