The invention relates to a lifting mechanism of a transport vehicle. The lifting mechanism comprises a slide rail and a slide plate which are vertically arranged, a lifting platform is pivotally connected on the slide plate through a horizontal overturn pin shaft, and a first distance is arranged between the overturn pin shaft and the slide rail; a shutdown spacer pin is fixedly arranged on the slide rail; a shutdown crank shaft is pivotally connected with the lifting platform through a horizontal articulated shaft, and the shutdown crank shaft is arranged on one side of the propped and positioned on one side facing to the slide rail by a horizontal bump arranged on the lifting platform, one end of the shutdown crank shaft facing to the slide rail is a hook-shaped spacing groove which extends to or extends beyond the lower position of the shutdown spacer pin and is used for being snagged on the shutdown crank shaft during the ascending process of the lifting platform along the slide rail, so as to draw the lifting platform to overturn around the overturn pin shaft and facing to slide rail. The lifting platform of the elevator mechanism of the invention equals to a rear door plate which can finish the operations of closing and opening automatically, thereby reducing the labor intensity of workers and improving the efficiency of loading and unloading.