Abstract: With the development of computer-aided design techniques, more and more complex design objects must be processed by the CAD systems, which makes it in evitably important to optimize the system in both space and time. The boundary representation model (Brep) and constructive solid geometry (CSG), which are the two main solid representation, cannot satisfy the real need of practical designs. By analyzing the boundary construction process, we propose a quick boundary regeneration algorithm by storing intersection lines in this paper. The algorithm is efficient in both time and space,which overcomes the shortcomings inherent to single Brep or CSG model.