Abstract: This paper puts forward the technical and economic significance of developing a low open circuit voltage transistor power source after analysing the GTA welding condition when using transistor power sources.The mechanism of no-toucharc-ignition with low open circuit voltage power source has been explored in order to find a theoretical basis for developing the new power source.By mathematical analysis of the welding circuit system,the authors investigated the influence of feedback units upon the process of arc stabilizing in the arc igniting period,thus making the optimal design of the circuit system for the welding power source possible.The paper gives also the technical parameters of the designed power source.The arc ignition has been proved to be very reliable in welding production.