In order to resolve the continued exhaust fault of safety valve which installed on the integrated pressure reducer, the test is designed and performed according to the configuration and operational principle and analysis of fault phenomenon and fault tree. The test and simulation result show that the damp properties of reducer of reducer valve is mismatch with safety exhaust flow is primary reason lead to this fault. Under the large flows condition, the reducer valve will be in the vibrate state which result in the valve worn and lead to the output pressure is increased slowly and finally over the open pressure of safety valve. Because of the exhaust flows of safety valve is more than the rated output flows, reducer valve loss the function of pressure regulation until gas of cylinder is entirely exhaust. The fault is resolved by change the damp characters of valve.