A wireless charging system, wherein the wireless charging system comprises a transmitter and a receiver; the transmitter comprises a transmitter coil and a first series matching capacitor, the transmitter coil is connected to the first series matching capacitor in series to form a first oscillation circuit, and the first oscillation circuit is configured to transfer power to the receiver; and the receiver comprises a receiver coil and a second series matching capacitor, the receiver coil is connected to the second series matching capacitor in series to form a second oscillation circuit, and the second oscillation circuit is configured to receive the power transferred by the first oscillation circuit; and the wireless charging system is configured such that, during power transfer, a transmitter self-inductance is L p, and a capacitance of the first series matching capacitor is C p; and a receiver self-inductance is L s, and a capacitance of the second series matching capacitor is C s, wherein L p * C p L s * C s = k, and k is a positive number not equal to one, characterized in that a unit of the wireless charging system is configured to: store a pre-determined mapping table, detect a position deviation between the transmitter and the receiver, and determine a first voltage gain based on the detected position deviation and the pre-determined mapping table, wherein the pre-determined mapping table includes a plurality of position deviations between the transmitter and the receiver, and, for each of the plurality of position deviations between the transmitter and the receiver, a pre-determined load-independent voltage gain, and wherein the unit of the wireless charging system is the receiver or the transmitter; and the wireless charging system is further configured to operate at a load-independent point when a voltage gain between an output voltage of the receiver and an input voltage of the transmitter is the first voltage gain; the load-independent point is determined by a first operating frequency and the first voltage gain; and at the first operating frequency, the first voltage gain is independent of an output load of the receiver. the wireless charging system is configured such that, during power transfer, a transmitter self-inductance is L p, and a capacitance of the first series matching capacitor is C p; and a receiver self-inductance is L s, and a capacitance of the second series matching capacitor is C s, wherein L p * C p L s * C s = k, and k is a positive number not equal to one, characterized in that a unit of the wireless charging system is configured to: store a pre-determined mapping table, detect a position deviation between the transmitter and the receiver, and determine a first voltage gain based on the detected position deviation and the pre-determined mapping table, wherein the pre-determined mapping table includes a plurality of position deviations between the transmitter and the receiver, and, for each of the plurality of position deviations between the transmitter and the receiver, a pre-determined load-independent voltage gain, and wherein the unit of the wireless charging system is the receiver or the transmitter; and the wireless charging system is further configured to operate at a load-independent point when a voltage gain between an output voltage of the receiver and an input voltage of the transmitter is the first voltage gain; the load-independent point is determined by a first operating frequency and the first voltage gain; and at the first operating frequency, the first voltage gain is independent of an output load of the receiver.