Abstract: Based on the CAN bus, using the incorporated control involving mechanical, electrical, hydraulic and pneumatic systems, a scheme of automatic control system used on the off-road vehicles is introduced. According to the characteristics of the transmission system, the automatic shifting, the control electro-circuit and the control software is designed. The manual operational function of automatic shifting is reserved, in case the system fails to function. The information of the vehicle are shared between the ASCS and other systems in order to optimize the capability of the vehicle and decrease the cost. The engine and the gear-box are controlled as a whole. Performance experiments showed that the system attained satisfactory results.