Abstract: Aiming at the problems of low production efficiency and out of tolerance of perpendicularity, symmetry and size of a robot arm, the arm structure is analyzed. A special fixture is designed for the arm parts by using the adaptive positioning method of V-groove and universal pin and the torque controllable of the clamping method. The practical application shows that this method improves the processing efficiency by 40.5% and the qualification rate by 98%. It meets the production demand, and solves a technical problem for the enterprise, and improves the economic efficiency.