In order to know about a series of changes happened in the cutting process of cutting TC4 alloy more clearly, the simulations are carried out based on three sets of its J-C model parameters under conditions of traditional and high cutting speed.Through comparison of the shapes of the chip and the cutting forces with experimental results, and iterative calculation, the friction coefficient and failure parameters of the materials were modified, and the simulation results obtained from the three sets of model parameters were compared to the experimental results, finally one set of parameters was chosen as the best. Under conventional and high speed machining process, the simulation results obtained from this set of model parameters had absolute advantages both in the shapes of the chips and the main cutting forces. The study results provide a reliable theory basis for the simulations of the TC4 alloy cutting process.