Abstract: Rotary tool cutting process is applied to cutting especially in difficult-to-cut materials cutting with its unique advantages. There is no literature about it. The rotary rate ratio that is the proportional relationship of “rolling”and “cutting”was presented for the first time based on analysis of rotary tool cutting processes was. Combined with the rotary rate ratio,machined surface quality and the contact sliding rate and milling force were studied. An inner driving rotary milling tool was first proposed in this paper. It is the hardware realization of the driving rotary milling tool. The rotary rate ratio of inner driving rotary milling tool not only can be adjusted before cutting processes in accordance with the requirements of parameters,but also can keep the adjusted value in machining process.Resultsshow that the inner driving rotary milling tool has a strong advantage,compared with the traditional self-propelled rotary tool.