To address the issue of deviation in the maximum efficiency point in wireless power transfer systems, caused by overlooking losses in inverters and rectifiers, a composite control strategy is proposed. This strategy combines maximum efficiency tracking with constant voltage output to minimize the optimal load deviation. Initially, the relationship between the parameters of the LCC-S type wireless power transfer system and the output voltage and current of each component is analyzed. A nonlinear rectifier bridge load equivalent model is developed to understand the impact of rectifier diode voltage drops on load conversion.Next, a system efficiency quantification model that incorporates losses from both the inverter and rectifier is created to quantitatively analyze the system efficiency as the load varies, thus reducing the deviation error in the optimal load. Additionally, LCC-S compensation parameters are optimized to enable zero-voltage switching operation for the inverter. On the secondary side, an impedance matching technique based on a Buck-Boost circuit is implemented for maximum efficiency tracking, while a Buck circuit is employed on the primary side to ensure stable output voltage control.Finally, an experimental platform is built to validate the theoretical analysis. Compared to traditional methods, the proposed strategy reduces the optimal load deviation error by 24.6%, increases the maximum efficiency by 1.1%, enables zero-voltage turn-on operation of the inverter across a wide load range, and maintains an overall system efficiency of approximately 90% with constant voltage output.