A high speed and high efficiency machining method is proposed to solve the problem of machining the connecting plate of the chassis of high-speed train. Based on the modal analysis of technological system and the dynamic model of milling process, the chatter stability domain of milling process is simulated by using the theory of regenerative chatter in cutting process, and the results of chatter stability domain related to technological parameters of milling process are given. On the basis of dynamic simulation, the main machining process parameters such as axial speed, feed rate, axial cutting depth and radial cutting depth are taken as design variables, and the minimum machining time is taken as optimization target to carry out optimization calculation, and the process parameters meeting certain optimization objectives and optimization conditions are obtained. It focuses on the optimization of CNC machining process parameters and the increase of metal material removal rate as the goal of high-speed and efficient CNC machining. The results show that the method can form the data handbook of aluminum alloy efficient cutting, the program and process specification of efficient CNC machining of typical aluminum alloy parts.