Abstract: This paper deduced the involute gear total tooth profile equations of unsymmetric teeth with double pressure angles, proposed the calculation formulas of coordinates and load angle at the upper and lower points of single and double teeth mesh areas, and programmed the relevant parametric programs. Compared with a standard involute gear, the unsymmetric involute gear could efficiently improve the tooth root bending strength by finite element analysis. Considering the time-variant mesh stiffness, the calculated results demonstrated the change of tooth root bending stress in one engagement period.