n the practical application of wireless power transmission technology in the field of UAVs, when the UAV lands due to the positioning accuracy and the control accuracy of docking there is error, will lead to inaccurate docking position and shift, due to the small size of the UAV, the size of the coupling mechanism will also be smaller, the offset at this time will lead to a decrease in the coupling degree of coupling mechanism, which in turn leads to the reduction of the efficiency of the wireless power transmission system, affecting the normal operation of the system. Therefore, in order to improve the anti-offset characteristics of the system, it is necessary to reasonably design and optimize the coupling mechanism of the UAV wireless charging system. In this paper, the coupling characteristics of different coupling mechanisms are analyzed and compared under the constraint of consistent line usage in combination with the structural characteristics of UAVs, and the optimal coupling mechanism suitable for UAVs is designed. Then, the parameters of the coupling mechanism are optimized for lightweight with M/l as the optimization goal. Finally, the feasibility of the coupling mechanism optimization method is verified by simulation and experiment.