In order to realize the rapid structure optimization of cycloidal pin gear reducer, the cycloidal gear is modeled with the tooth profile equation of cycloidal wheel firstly. The stress of cycloidal pin gear reducer was analyzed theoretically, and the force of the cycloidal gear in motion was obtained. Parametric design on cycloidal pin gear reducer was completed by using Creo20 Pro/toolkit tools and Visual Studio2010, which improved the work efficiency. The assembly of cycloidal wheel and pin gear was analyzed by ANSYS software and the rapid structure optimization of cycloidal wheel was realized by parameterization of cycloidal wheel The method of parameterized design effectively solves the problem of low efficiency in the optimization of cycloidal wheel structure, and provides the basis for the optimization of other parts of cycloid gear reducer.