Abstract: In this paper，an algorithm for Boolean operation between sculptured models is presented and the accuracy，efficiency and robustness are the main considerations．The solid model is represented with the trimmed parametric patches and half-edge data structure．Hierarchy intersection is applied for unified classification，and tracing the intersection curve to overcome degenerate cases occurring frequently in practice is also used．It can easily be extended to Boolean operations for non-manifold models．The algorithm as a part of a modeling system on a SGI workstation is implemented．