A mounting assembly is configured in a case having an opening and a door panel. The door panel is pivoted to the case so as to cover the opening or uncover the opening by removing the door panel. The mounting assembly includes at least one fixing rod, a stopper member, at least one elastic member and an actuator. The fixing rod is disposed on one inner side of the case adjacent to the opening. The stopper member and the elastic member are movably disposed on the fixing rod. The actuator is disposed on the door panel. When the door panel covers the opening, the actuator is incorporated with the stopper member, such that the stopper member shields the opening, so as to avoid an object moving around or away from the case through the opening.