In order to use computer to carry out quick, accurate and economic design of product shape and colour, a package of AUTOLISP programs was developed which can be run under AUTOCAD main environment.Due to the limitation of AUTOCAD 11.0 and 12.0 in 3-D design of complex curved surface, the 3-D design functions were enhanced in the following aspects: (1)3-D line JOIN and BREAK commands were developed to join and break 3-D polylines. SPIRAL command was designed to create 3-D cone or cylindrical spiral line. In addition, EFTURN and MEFTURN commands were developed to change the vertex sequence of polyline totally or midway. (2)3-D elements and characters Existing subroutines were revised to directly generate Box, Cone, Pyramid, Dome or Dish, Torus, Sphere and Wedge ready for solid modeling. Furthermore, CONVEX, HOLE and TUBE commands were developed to generate different kinds of convex, hole and tube respectively. A set of 3-D characters was made. (3)3-D operation EXTRUDE and SKIN commands were developed to enhance the function of TABSURF and RULSURF commands in AUTOCAD. (4)3-D edit and assembly The TOP, FRONT and SIDE commands were designed for 3-D assembly of different parts independently in three planes. Finally, as a demonstration, a complete mechanic product was designed by using the package introduced in this paper.