The use of bilateral collaborative control wireless power transfer system with the original and secondary sides are fully controlled H bridges can greatly improve the flexibility of system control, when using the control strategy of primary side frequency tracking and secondary side phase shifting, if the system deviates from the primary side resonant frequency, theremay be non-monotonicity of power regulation, so that the control logic fails or even the system is damaged. In this paper, the conditions for monotonic power adjustment are derived from the perspective of impedance matching, the critical impedance is calculated, and the impedance equivalent is performed by the secondary side phase shift, and the power regulation control strategy is optimized. The simulation and experimental results are in good agreement with the theoretical analysis, and this study has potential application value for the study of system power regulation and impedance matching.