A mounting apparatus is provided for mounting expansion cards. The mounting apparatus includes a rear panel, a retainer, and a clip. The rear panel has a support wall for supporting the bent portion of the cover plate, the rear panel defining an opening for facilitating installing or removing the expansion card. The retainer has a pressing plate pivotally coupled to the support wall. The clip has a resilient member for securing the retainer to the rear panel. The retainer has a fixing member for clasping the bent portion of the cover plate when the retainer is rotated to a first position and unclasping the bent portion of the cover plate if the retainer is rotated to a second position.