Abstract: A new automatic shift system driven by a DC motor for an automatic mechanical transmission (AMT) is proposed. The system consists of a clutch control system and a fuel stop valve for the diesel engine. The former adapts the two-parameter PD shift on the speed of rotation of the clutch output shaft and that of the differential between the input and output shafts. The latter realizes an on-off control of fuel to regulate the output torsion and speed of rotation of the diesel engine when shifting. Test results indicate that the shift system improved gives shift performance to the vehicle.