In wireless power transfer (WPT) systems, the transfer efficiency will be significantly affected by coils misalignment or power variation by traditional control strategy. In this paper, a variable-frequency asymmetrical-phase-shift (VFAPS) control strategy is proposed, which simultaneously controls the system frequency and phase shift angles to regulate the transmission power with maximum transmission efficiency regardless of coils misalignment or power variation. System frequency is controlled to compensate the reactive component of the secondary circuit. Asymmetrical-phase-shift can reduce reactive power loss and narrow the regulation range of system frequency on the basis of a wide range of ZVS. Finally, a mathematical model for solving the optimal control variables is established. Contrast experiments with the traditional triple-phase-shift (TPS) strategy on a 3.7kW WPT platform are constructed to verify the effectiveness of proposed strategy. The results demonstrate VFAPS strategy enables the system to operate at maximum efficiency and has great advantages in resisting coils misalignment and power variations.