A wireless charging circuit includes a substrate. The first surface of the substrate includes a first metal wire, which is spirally disposed on the first surface. A second metal wire is disposed on the second surface of the substrate. An end of the second metal wire is electrically connected to an end of the first metal wire. The second metal wire further has a first extending portion on the second surface; wherein the first extending portion is corresponding to the first metal wire and the length of the first extending portion is smaller than a half of that of the first metal wire.