If the pressure is abnormal and the amount of gas discharged by the compressor can not meet the user's flow requirements under the rated pressure due to the reduction of the exhaust pressure, the exhaust pressure must be reduced. The reduction of the required exhaust pressure is a phenomenon, and its essence is that the exhaust volume can not meet the user's requirements. At this time, we have to change another machine with the same exhaust pressure and large exhaust volume. The main reasons that affect the abnormal interstage pressure are the gas leakage of the gas valve or the gas leakage after the piston ring is worn, so the reasons and measures should be taken from these aspects.