According to the requirements of integral Stereolithography (integral SL) System, a new direct slicing method with SolidWorks for integral Stereolithography System is developed. Slicing function of SolidWorks is employed to slice CAD models directly, and section image of 3D models can be obtained and saved as image format. Dynamic graphic masks for the integral SL System are created according to the cross-section images that obtained through the slicing method, and then 3D real prototyping can be fabricated conveniently. A 3D cup model is sliced with this method, and the cup prototyping also is built with integral SL System. This experiment shows that direct slicing CAD models with Solidworks can be used for integral SL system, and the method of direct slicing CAD models can improve the efficiency of slicing process. Compared with the STL format files slicing method, the new method does not need to inspect and repair models data, and it can achieve high accuracy of layer section profile. The direct slicing method provides a basis for integral SL system to fabricate objects with high accuracy.