On the base of analysis classic methods, the morphologic addition algorithm for convex polyhedron is predigested to the morphologic addition of faces in polyhedron. The concept of reference plane is introduced with the model of normal vector sphere for 3D objects, the convex polygons in 3D space are divided into two parts by the reference plane and morphologic addition of each corresponding part is calculated. Then the repetitionary faces and edges are deleted, a fast morphologic algorithm for convex polyheron is presented. The experimental results show that this method is 6～10 times faster than classic methods and works well.