It utilizes transducer and alternative-current servo motor to control the bag making speed and film traction positioning. The tension of the entire machine is controlled by the cylinder through pressure regulator in order to acquire flexible air control and flexible plastic film. The electric control makes use of the industrial control computer processed signal.The tension of the magnetic powder stop dog is controlled by degressive simulation. The settings of a series of data including bag making speed, alarm triggering quantity, working mode and temperature etc. are all entered by the keyboard and displayed on the screen, which is convenient for direct perception and easy to operate.