Modeling for generation of involute helical gear tooth surface with precious fillet surface is provided in this paper. Based on the surface generation of gearing theory, the generated tooth surface is derived by the generating surfaces of rack cutter. The complete projection mapping of cutter and tooth surface is established and accurate tooth profile is modeled with composition points. All these advanced geometry properties are integrated in a FORTRAN program. Some important features for contact analysis are calculated rapidly. The simulation result shows that the precise modeling with surface action developed is generic and can facilitate the generation of complicated tooth surface with modification. It is effective to model the actual tooth profile for bending stress with this method.