A finite element model (FEM) of high-speed cutting was built to study the mechanism of high-speed machining of alloy cast iron used widely in auto panel dies. The mechanics properties of workpiece material were obtained in the conditions of high strain-rate, high temperature and high strain through high-speed impact compress experiments. Several key technologies are studied such as friction and chip-tool heat conduction. The cutting temperature, stress distribution, and the chip formation process in the process of high-speed cutting alloy cast iron were analyzed based on the finite element model, which was validated through cutting force experiments. It shows that the FEM can simulate the high-speed cutting process of alloy cast iron materials.