In order to improve the control speed of a Dynamic Wireless Power Transfer (DWPT) system and ensure voltage stability and high efficiency of the system during dynamic charging, a control method is proposed based on estimation of mutual inductance of a double pick-up coupling structure. By building the mathematical model of output voltage and power, the relationship between the optimal duty cycle and parameters including mutual inductance and equivalent series resistance of each pickup circuit is revealed. A closed-loop control method by directly calculating the duty cycle is presented. In the case of no communication connection with the transmitting side, the proposed control method can improve the control speed of the pick-up circuit and realize constant output voltage and efficiency optimization simultaneously. The experimental results show that with the proposed control method, the output voltage at the load side is constant during load moving. The output voltage fluctuation is within ±0.988%, and the maximum efficiency of the system is 93.18%. The experimental results have verified the validity of the proposed control method. This work is supported by National Natural Science Foundation of China (No. 51607150).