To study the thread milling of superalloy， the definition and expres sion of uncut chip thickness are proposed， and the expression method of section area between two passes is introduced. On the basis of these concepts， the threa d milling cutting force and torque of superalloy are studied. The result shows t hat thread milling cutting force and torque are positively related to section ar ea. In the process of superalloy thread milling， the radial depth of cut is opti mized by the same section area at every cutting step. The optimization method of cutting force and torque can improve part precision and tool life， and can be t he theoretical basis for processing technology of thread milling of difficult to machine material.