Abstract: A novel PWM-BUCK type of high-voltage accelerating stabilized power source system for electron beam welder is introduced,and the switch current-limiting circuit is built to prevent surge current and over-current,which increase the system reliability and stability.By means of SABER simulation,the open and closed loop characteristics of the system are analyzed in detail.A PID controller with power supply feed-forward compensation for the voltage control is proposed,and the setting principle and procedure of parameters for the controller are discussed.The simulation and application results show that this system has high control precision,good dynamic behavior,high energy conversion efficiency,low working condition requirements and high working reliability.