The screen changer is an automatic switching device including one or more filters, which is used to filter out foreign particles and impurities when the plasticizing material flows into the filter screen. The filter screen is supported by an alloy porous plate which is mounted on a plate or column type carrier. The screen changer can be installed in any new or existing extruder, melt pump, reactor or other extruder production line. The double plate and double position quick screen changer can automatically compensate the sealing gap. It is resistant to high temperature, high pressure, no material leakage, large filtration area and suitable for high-yield equipment. It can increase the output and save the energy consumption. It is convenient to change the net and easy to operate and maintain. It is widely used in the extrusion production line of granulation, pipe, plate, sheet and tape casting film.