A method of reciprocating compressor fault diagnosis based on vibration sign al analysis was presented. Firstly, frequency band energy criterion was used to determine the response signal frequency band, which was caused by the varying cylinder p ressure. Secondly, comb filter was adopted to acquire the signal fr om the cor responding band. Thirdly, the envelop of the filtered signal was extracted. Fina l ly, the envelope curve was used to construct a simulation indicator diagram to ma ke further diagnosis of reciprocating compressor faults. The application result shows that it not only can be used to distinguish the fault state from the normal of the compressor, but also can be used to divide the fault into different ty pes, which make it valuable in practice.