Abstract: In a method and apparatus for producing polystyrene tubular shrink film via film blow molding, a polystyrene plastic material is extruded into a circular tubular film, which is cooled and then uniformly heated in a special hot water tank to become softened. Hot air is then blown into the softened tubular film, and two sequentially arranged speed-controlled pressure guide roller sets are set to two different operating speeds, so that the softened tubular film is transversely and longitudinally stretched and thinned to form a stretched tubular film, which is then passed through a setting treatment system to form a thermally set tubular film and be finally wound in a take-up system into a roll for storage. The method and apparatus is simple, low cost, and easy to operate, and the product thereof is environment friendly to help in economic development.