Abstract: Compared with traditional machining processes,the plastic forming of big spiral teeth shafts has obvious advantage of high production efficiency and material utilization,but the forming of proper tooth graduation is difficult. The parametric equation of die profile curves,closely related to transmission ratio,was established in this article. The law of transmission ratio between die and workpiece was studied by finite element simulation,and the reliable transmission ratio variation and die profiles were obtained. Taking the driven rotor as an object of study,the proper tooth graduation of big spiral teeth of the driven rotor was realized by fixed cross rolling experiment to solve the problem of proper tooth graduation.