To synchronize the power transmission of inductive wireless power transmission (IWPT) control systems with signal sampling and feedback on the secondary side, a variable capacitance signal reverse transmission method is proposed. Because the input impedance angle of the primary side can be changed by modifying the secondary-side compensation capacitance, this method realizes signal transmission by characterizing the phase change as a digital signal. First, the equivalent circuit model of the system is established using the first harmonic approximation (FHA); the relationship between the secondary-side compensation capacitance and the input impedance angle of the primary-side is analyzed, and a modulation and demodulation strategy for the signal is proposed. The method for selecting the modulation capacitance and maximum transmission rate, and the influence of the signal reverse transmission rate on power transmission are then given. Finally, the effectiveness of the method is verified through simulation and experiments. The results show that the proposed signal reverse transmission method can effectively modulate and demodulate the signal when the load and mutual inductance change, correctly transmit the digital signal, and have no impact on power transmission.