Abstract: Performance evaluation for multi-cyclone separator in some inland metering station of natural gas pipeline with on-line detection device in high-pressure gas pipelines was carried out in 2008 and 2009. 2008' s report showed that the cyclone separator in this station had low efficiency, with an average efficiency of only 62.4%. Based on this report, the authors analyzed the cause of low efficiency for the cyclone separator, and proposed the basis in type selection of cyclone separator. The cyclone separator was replaced with a new one in 2009, and theseparation efficiency of the new cyclone separator increased to 90.6%, with better dust removal effect. Dust on-line detection devices in high pressure gas pipelines can realize on-line detection of dust in gas pipeline with safety, reliability and good real-time performance and high precision, which can provide a guidance to performance evaluation and type selection of separation and filtration equipments.