The invention discloses a tire forming drum. The tire forming drum comprises at least two positioning mechanisms separately arranged on two sides of the tire forming drum, and the positioning mechanisms comprise fixing blocks disposed on one side of the tire forming drum, driving units fixedly connected to the fixing blocks and connecting rod assemblies separately connected to the output ends of the driving units and the fixing blocks and provided with an extended state in which the surface of the corresponding tire forming drum is pressed and a contracted state in which the surface of the corresponding tire forming drum is not pressed. The driving units drive the connecting rod assemblies to switch between the contracted state and the extended state to match the tire forming drum to takeup tire components. The sizing material positioning mechanisms have a simple structure and good stability, and can effectively press the head end of the tire components, thereby assisting the tire forming drum to perform material rolling.