A locking mechanism for the packing case of vehicles comprises a lock lever, a handle for the lock lever, a supporting frame for the lock lever and a fixing board for the handle. The lock lever is vertically fixed with the handle for the lock lever which can revolve the lock lever which is rotatablely supported on the packing case door by at least two supporting frames for the lock lever. The part of the supporting frame that can rotatablely support the lock lever hangs out of the lower door frame and matches with the lock base fixed on the lower door frame of the packing case. Two ends of the lock lever can have a set of lock head respectively. The utility model can open and close the door of the packing case safely, conveniently and effectively.