Abstract: In order to deeply explore the tooth surface design and meshing characteristics of non-orthogonal asymmetric helical face gear, the tooth surface shape of non-orthogonal asymmetric helical face gear is accurately obtained by establishing and solving the meshing equation. The improved potential energy method is used to calculate the time-varying meshing stiffness of non-orthogonal asymmetric helical face gear under different pressure angles and shaft angles, and the calculation results are verified by finite element simulation technology. The results show that when the shaft angle is fixed at 60°, the time-varying meshing stiffness of the non-orthogonal asymmetric helical face gear increases significantly with the pressure angles of 15°, 20°, 25° and 30°, respectively. When the pressure angle is fixed at 20°, the time-varying meshing stiffness of the non-orthogonal asymmetric helical face gear decreases with the increase of the shaft angle when the shaft angle is 30°, 45°, 60° and 90°, respectively. Therefore, increasing the pressure angle from 15° to 30° or reducing the shaft angle from 90° to 30° can significantly improve the time-varying meshing stiffness of non-orthogonal asymmetric helical face gear. This characteristic is helpful to optimize the reliability of non-orthogonal asymmetric helical face gear transmission system, and provides important theoretical support for related design and application.