Abstract: The calculation formulas of general curvature radius and tooth face contact stress of the unsymmetric gear with double pressure angles were proposed at the upper and lower points of single and double teeth mesh areas and the pitch point. The given parameters were calculated by analytic method. Parametric design programs of the total tooth models of unsymmetric and symmetric involute gears were developed by Autolisp language, and the total models were transferred into ANSYS and calculated by finite element method. Compared with the standard involute gear, the two methods showed that the unsymmetric involute gear could efficiently improve the tooth face contact strength. Considering the time-variant mesh stiffness and curvature radius of mesh points, the change of tooth face contact stress in one engagement period was demonstrated.