A method for manufacturing a wireless charging device is disclosed. The method includes: providing a substrate, a first metal plate, and a second metal plate; forming a plurality of circles of slots, each of the circles of slots including at least one first slot and at least one second slot, the at least one first slot having a first depth, and the at least one second slot having a second depth; forming a first coil and a second coil by performing a metal forming process on the first metal plate and the second metal plate; and placing the first coil in the at least one first slot, and placing the second coil in the at least one second slot. In the method, the first coil and the second coil have good fixity and are easily to be assembled.