Abstract: A direct slicing approach from 3D CAD models is proposed by studying the data structure of SolidWorks solid models and the method of obtaining geometric and topological information from SolidWorks CAD models.Based on SolidWorks platform,a direct slicing program has been developed,in which surfacesurface intersection function of application programming interface （API） is called to get the section contours.Tool path is generated by sorting the section contours end to end.Raster filling algorithm is studied and implemented to compute the tool path for filling.The slices data are saved in a special file in which lines,arcs and circles are used to describe the section contours.The file is independent of SolidWorks.The direct slicing result is simulated.Part fabricated with application of the direct slicing software is compared with that based on stereolithography （STL） format.It is shown that the accuracy and surface finish of the direct slicing part is better than that of STL indirect slicing.