A quick assembly apparatus includes a fastening unit, a control unit and an elasticity unit. The fastening unit includes a head section and a fastening section, a through channel connecting the head section and the fastening section, and a notch at the fastening section to form a plurality of elastic fastening elements. The control unit is movably inserted in the through channel, includes a supporting section supporting the elastic fastening elements, a control shaft connected with the supporting section and extending out from the fastening section, and an extension shaft connected with the supporting section and extending towards the head section. The elasticity unit is fitted around the extension shaft of the control unit, and has its one end pushed against the control unit and its another end pushed against the fastening unit. Accordingly, the quick assembly apparatus is capable of quickly and steadily assembling two plates.