Abstract: According to the space object frustum clipping, a kind of precision optimization method has been put forward that is based on the convex hull.First of all, the method get the 2d plane projection from 3d object, and organize projective coordinate to a convex hull, finally get the visibility of objects according to the line form the coordinate of convex hull and the camera, whole optimization needs any extra memory to save the data of convex hull only. The experimental results show that this method implement simply, it can reduce the unreasonable result from the sphere detection or cylinder detection, improving the whole efficiency of 3D rendering system.