As a new worm drive, it is difficult to choice parameters of planar internal gear primary-enveloping crown worm drive for the acquisition of the excellent meshing performance. Aiming at this question, the meshing performance equations are established basing on the theory of differential geometry and gear meshing. A new multi-object parameters optimization method is presented based on the macroscopic meshing performance and the microcosmic meshing performance. Based on its characters, the equation is solved ...