Using the splitting property of tringular Bézier patch, the problems of iterating and initial intersection point calculating can be solved. By the procedures of near surface point iterating and border points traversing, the whole intersection curve traversing many patches can be traced from one initial intersection point. Inserting intersection points as measure points into surface, retriangulating grids, splitting triangular grids and measure points along intersection curve, the original surface can be trimmed into two composite triangular Bézier surfaces. The experimental results show that this method is simple, robust and applicable for surface modeling.