Ring welds are a kind of welds commonly used in the production of pipes,containers,chemical equipment,etc. Due to their many welding positions,poor accessibility of manual welding and difficulty in welding,various forms of automatic ring seams are often used in actual production. The welder replaces manual welding. However,the current automatic seam welder still has problems such as low production efficiency and narrow adaptability. According to the actual production needs,this paper uses ordinary positioner and the most common gas shielded welder to transform. Through the powerful automatic control function of PLC,multiple torches are controlled at the same time,which realizes automatic and efficient ring weld welding. The system is simple in structure. High production efficiency and powerful function,especially suitable for the welding of coaxial multi-channel annular welds.