Abstract: The causes of interference in the propagation of the bat-handle switch and arc voltage signal are pointed and their affections to arc welding machine are analyzed.Two useful anti-interference transmission circuits toward the two signals are designed. Drooping characteristic pulse transformer is used to ensure isolation between working signal and interfering signal in bat-handle switch signal transmission circuit.LC filter and linear-optocoupler are used to ensure the accuracy of sampled arc voltage in arc voltage sampling circuit.The test shows that the two circuits are simple, reliable and easy to operate and play an important role in increasing anti-interference characteristic of control circuit.