The air pressure reducing valve setter consists of three parts: 1. The main closed part of the direct acting pressure reducing valve; 2. The constant pressure drop device, which is equivalent to a certain differential pressure reducing valve. The main function is to make the nozzle obtain the stable gas source flow; 3. The nozzle baffle device and the pressure regulating part play the role of pressure regulating and pressure amplification, and use the enlarged air pressure to control the main valve part.