A wireless charging method for charging an underwater moving device is implemented by a charging device. The charging device receives electricity from a cable, and includes a first underwater wireless communication unit, a position holding unit, a first control unit, and a wireless charging transmitter. The underwater moving device includes a second underwater wireless communication unit, a wireless charging receiver, and a rechargeable battery. The first underwater wireless communication unit obtains moving device information by communicating with the second underwater wireless communication unit. The position holding unit holds the underwater moving device at a charging location, and generates a positioning success signal after the underwater moving device is held at the charging location. Upon receiving the positioning success signal, the first control unit controls the wireless charging transmitter to charge the rechargeable battery based on the moving device information.