An overlap subdivision method was proposed in order to generate C1 continuous tool-path offset circles. On the basis of this method, a spiral tool-path generating algorithm for imitating human polish behavior has been produced. Only common algorithm (Non A.I.) was used to simulate human polishing. A kind of spiral tool-path was generated by using the overlap subdivision method to cut out all the zigzag turning and sharp corner of the patch boundaries except the edges of work-piece. This tool-path could be used in the field of high speed milling and polishing for freeform surface. A concept of overlap ratio was defined with which we got the evaluation of the machining efficiency of the tool-path and a proper range of overlap subdivision density was recommended. The machining overlap ratio can be adjusted with only a weight parameter w1. Simulation and test have been done with Matlab so as to verify the effectiveness of the entire algorithm.