The invention discloses a method of using an auxiliary support to mount an integrated ballast bed reinforcement in situ in an overhead manner. The method of using the auxiliary support to mount the integrated ballast bed reinforcement in situ in an overhead manner comprises the steps of making tripods of two expansion joints and matched members; fixing top channel steel and inserting galvanized steel pipes into the tripods; placing longitudinal reinforcements, sleeving a hoop and binding the longitudinal reinforcements as required; inserting side reinforcements and bottom longitudinal reinforcements into the hoop and binding the side reinforcements and the bottom longitudinal reinforcements as required; pulling manual hoists at a constant speed to integrally lift the reinforcements; and putting the whole integrated ballast bed reinforcement into a foundation groove. According to the method of using the auxiliary support to mount the integrated ballast bed reinforcement in situ in an overhead manner, as the operation surface of the track foundation reinforcement project is transferred from the interior of a track foundation pit to a position right above the foundation pit by using members such as the special tripods, the galvanized steel pipes, the reinforcements, the channel steel and hooked reinforcements, the distances between the reinforcements can be preferably controlled,the binding of the reinforcements are more convenient and faster, the quality of the track reinforcement project is integrally improved, the integrated ballast bed reinforcement binding working spaceis increased, the construction period is reduced, the labor is saved, and the the construction of the integrated ballast bed reinforcement project can be rapidly finished.