The invention provides a wireless charging system and method. The wireless charging system comprises a wireless charging transmitting device, a relay transmission device and a wireless charging receiving device; when sensing a magnetic field generated by a first transmitting coil, a second receiving coil generates alternating current; an impedance matching network circuit is adjusted according tothe working frequency of the wireless charging transmitting device, so that the alternating current is reduced, and a magnetic field is generated through a second transmitting coil; when sensing a magnetic field generated by the second transmitting coil, a first receiving coil generates alternating current and the alternating current is converted into direct current for charging a wireless charging device. According to the embodiments of the invention, the impedance matching network circuit is adjusted, so that the alternating current is reduced, and the electric energy transmission distance and transmission efficiency of the wireless charging system can be improved.