Abstract: Using the VUMAT subroutine embedding method, the stress-strain relationship in the elastic deformation stage of the polyimide polymer material is described, and the effects of the cutting process parameters on the cutting force of the polyimide milling process are analyzed through the three-dimensional thermal-mechanical coupling finite element model. The influence law on cutting force, temperature and chip morphology of the polyimide milling process is analyzed through the three-dimensional thermal-mechanical coupling finite element model. The result is that as the feed rate increases, the simulated cutting force and cutting temperature increase as well, and the degree of banding of chips will become serious. Subsequently, the cutting experiment was used, and the cutting force difference between the simulation and experiment was up to 18%, and the cutting temperature difference was up to 23%. When the feed rate increases, the degree of chip curling increases and the surface texture becomes deeper. When the feed rate is 0.15 mm/r and 0.45 mm/r, the chip edge tears. Defects such as adhesion, drawing, and layup of tiny chips on the machined surface of the workpiece cause the material microporous flow channel to be blocked. This constitutive model has certain universality to polymer materials. The validity and accuracy of the simulation model have been verified, and the optimal milling process parameters for polyimide have been obtained: milling depth (a_p) is 1 mm, milling speed (v) is 75 m/min, and feed amount f = 0.20~0.30 mm/r.