To improve the design of complex curved parts and the shortage of reading two-dimensional drawings. This paper explicitly discussed modeling the bottom of a bottle by enhanced modeling and rendering techniques of CAD/CAM. Established the bottom with freeform surfaces in UG to solve the problem of design a part with freeform surfaces, and rendered the bottom of the bottle to express the result of three-dimensional stereoscopic of a part with freeform surfaces. Rendering is setting the material and texture for the model, and then adding lights and setting the background, etc to help solving the problem of identifying a part with freeform surfaces. Finally, we got the features of UG, the advancement, applicability of CAD/CAM and the necessity of expanding it.