Negative pressure angle spiral clutch is widely used in the drive axle main reducer assembly of heavy trucks because of its advantages of strong bearing capacity, good meshing performance and high transmission reliability. The design technology of the key components of the special gear milling machine for machining negative pressure angle spiral clutch was studied, and the mathematical model of gear milling was established. According to the machining characteristics, the structure and function of the cutting tool box and workpiece box were analyzed, and the equivalent machine tool model was established based on simulation software. The machining program was compiled and the simulation and analysis of convex and concave teeth were completed.It verifies the correctness of the design scheme of gear milling machine.