As shown in the figure, the dynamic contact equivalent stress of helical gear and the history curve changing with time are given. As the thermal mechanical coupling analysis requires a lot of computer resources, we only analyze the short load step. From the curve, we can see that the maximum contact stress of helical gear is consistent with the curve considering only mechanical factors. This is because the helical gear just starts to operate and the speed gradually increases, At the beginning of friction heat generation, the temperature failed to be dissipated through convection and other heat transfer methods in time, so the maximum contact stress at the meshing point of the helical gear gradually increased, and the torque remained unchanged. With the increase of the helical gear speed, the convection heat transfer capacity became stronger, and the maximum contact stress of the helical gear began to decrease.