A mounting apparatus for a fan includes a bracket, two fixing members, two screws, and a shield plate. The bracket includes a fixing plate defining a vent and two first through holes adjacent to opposite ends of a top of the vent. The screws extend through the fixing members and the first through holes of the bracket, in that order, for engaging in an upper portion of the fan arranged behind the fixing plate, with the vent aligning with the fan. A top of the shield plate is rotatably connected between the fixing members. The shield plate hangs vertically by gravity to cover the vent upon a condition that the gravity of the shield plate is not overcome by airflow passing through the vent.