Abstract: To improve the machining efficiency and avoid making mistakes when NC program members devide the surface into many patches and plan the tool path for each patch according to their experiences and characteristics of the sculptured surface,the paper presents a new method for surface patching machining.First,the machining surface is classified according to similar symbol and surface local characteristics.Second,the points with similar machining characteristics are put into a patch based on k-means clustering.Finally,after patching surface,the tool paths are generated by different planning methods for each patch,and the tool mark is controlled at the adjacent area.The example shows that the method can reduce the length of the tool path and improve the efficiency.