Abstract: Torque converter works on high-speed rotation state. Its upper cover and pump wheel have very strict concentricity trueness requirement after the assembly welding. The factors, influencing the concentricity of upper cover and pump wheel after assembly TIG tack welding with wire, are discussed in details, which include workpiece state, workpiece structure, mechanical state, welding technology and so on. With introduce of Tureness-error principle, the concentricity accuracy composition of TIG tack welding with wire system for torque converter is analyzed and designed quantitatively. A concentricity accuracy control mathematic model of the system is put forward. The concentricity accuracy composition method and the composition coefficient ascertain method are also discussed. Through analying and resolving of the model, the tool set up requirement of the upper cover and pump wheel,which meets the production concentricity accuracy, is gained with relatively low cost. A manufacturing system sutiable for practical production is also developed.