A mounting apparatus includes a chassis and a mounting piece. The chassis includes a rear plate. An expansion slot is defined in the rear plate, and a clipping portion extends from an edge of the expansion slot. The mounting piece includes a main body, an engaging piece extending from a first end of the main body, and an inserting portion extending from a second opposite end of the main body. The engaging piece defines a clipping slot, and two blocking portions are located on the opposite side of entrance of the clipping slot. The clipping portion is engaged in the clipping slot, and the two blocking portions prevent the clipping portion from being disengaged from the clipping slot.