For pulsed TIG power source controlled by microcomputer, the electromagnetic disturbance occurred frequently during arc ignition. In order to suppress the disturbance, a new high-voltage pulse arc ignition device is discussed in this paper. By using a special output transformer, a new inverter topology is designed; thus the lower cost and smaller volume are realized. Under the working condition of 50m cable,are ignition distance can reach 10to 12mm and the microcomputer control system works reliably.