In order to solve the problem of efficient machining of internal helical gear,a method for machining internal helical gear by power skiving was put forward.According to the machining principle of internal helical gear power skiving,the mathematical model was established.The equation of cut tooth surface was established and the equation of internal helical gear was derived.An internal helical gear was simulated in Vericut to verify the correctness of the theoretical model.Finally,the cut experiment was carried out,the workpiece was measured,and the precision of tooth met the engineering requirements.The results show that the proposed power skiving method can complete the efficient machining of the internal helical gear and has theoretical and engineering application value.