A new control strategy was presented which combined the advantage of the electric power assist control strategy and the real-time optimization control strategy. Based on the new control strategy and the configuration and performance requirement of the hybrid tow tractor, the logic control system was designed which had five states and 20 transitional phases, the actual relationship between ICE and electric motor on light-duty was extracted from the testing data, at the same time the distribution of torque was optimized in real-time with PD controlling method. The testing results showed that the control system achieved the control objectives which were expected and transferred power smoothly under state-switch.