The invention provides a tire molding machine and a boosting turning-up method thereof. With the adoption of mechanically-boosting turning-up method and device, mechanically-boosting devices at the two sides of a molding drum simultaneously, equally and continuously provide axial thrust to capsules or turning-up rods, so as to assist the capsules or the turning-up rods to finish the whole turning-up process, realize the stable-pressure and uniformly-distributed turning-up operation, and improve the tire molding quality. The boosting turning-up method comprises the following steps that: the molding machine comprises a belt layer drum which is loaded and driven by a belt layer drum chassis, and the molding drum which is loaded and driven by a molding drum chassis; the side part of the belt layer drum is axially provided with a first boosting device and the side part of the molding drum is axially provided with a second boosting device; and in the process of preparing a tire in a turning-up manner, the first boosting device and the second boosting device are symmetrical along the vertical center line of the molding drum, and the first boosting device and the second boosting device push the capsules or the turning-up rods from the two sides of the molding drum to the center, so that the same thrust is applied to carrying out turning-up operation in an assisting manner.