Abstract: A drainable wireless charging device includes a power emitting unit assembled on a first connection member in a waterproof manner and a power receiving unit assembled on a second connection member in a waterproof manner. The first connection member and the second connection member respectively have an insertion groove and an inserting portion for inserting into the insertion groove. The insertion groove has a second attaching surface corresponding to the power receiving unit. The inserting portion has a first attaching surface corresponding to the power emitting unit. The first connection member and the second connection member, and the first attaching surface is closely attached against the second attaching surface, so that water can be drained from the space between the first attaching surface and the second attaching surface.