The tailgate power unit is a power unit used for the control of the tailgate of a box truck. It uses a two-position three-way solenoid valve and an electromagnetic check valve to realize actions such as lifting, closing, descending, and opening the tailgate to complete the cargo. Loading and unloading work. The descending speed can be adjusted through the throttle valve. Since the power unit of the tailgate of the car is designed by itself, it has the characteristics of convenient installation and maintenance, and simple operation, so it is suitable for horizontal installation.