Planetary compound milling method is a kind of realization form of compound machining method. The cutting force of planetary compound milling method is much lower than that of ordinary end milling method, which can effectively reduce cutting heat, reduce workpiece deformation and increase tool life. The main reason why the cutting force of planetary compound milling method is greatly reduced is that the cutting path of this method makes it possible to decompose the thick cutting layer into the fine cutting layer, and the spiral angle of the end milling cutter and the radius of the end milling cutter have little influence on the actual cutting force. High-speed cutting could be achieved by the planetary composite milling method when the cutter head rotated at low speed, effectively avoiding the problem of dynamic balance of high-speed rotating cutter head, combined with its advantages of small cutting force, by increasing the diameter of cutter head and increasing the number of end milling cutters to improve processing efficiency. The planetary milling cutter adopts planetary gear train structure, which can meet the cutting path requirements of planetary compound milling method, and has the advantages of large torque and reliable operation.