Abstract: The conventional tool path generation algorithms are difficult to meet the demands of high speed machining.To solve this problem,a direct spiral tool path generation method with constant scallop-height is proposed.According to the different connections of the first and last boundary curves,this method involves three different ways to generate the initial spiral tool-path.Then the contour offset procedure works along the initial spiral tool-path,and the offset distance is determined by the scallop height.Compared with the spiral tool-path generated by determining the diagonal curve between the circuit tool-paths,the tool-path generated by this method can ensure higher level of quality of the surface being machined,and has longer single tool-path with less tool-path sharp corners.The simulation result shows that the method proposed could effectively meet the needs of high-speed machining.