Abstract: In order to evaluate the purification performance of multistep dedusting and deoiling purification unit, the configuration and performance were described by analyzing the operation of the purification unit in a single gate station at Shanghai Natural Gas Pipe Network. In the process, the flow state of particles and airflow in the system were simulated. Besides, the dedusting and deoiling effects, operating differential pressure, and trapping contents of impurities (oil, water and dust) were studied. The results showed that gradient multistep dedusting and deoiling purification plant had an initial differential pressure of 0~1 kPa. After running for 30 days, the pressure drop was only 5~6 kPa while the weight of the pollutants captured by the density gradient filter layer was up to 615.3 kg and the weight of the impurities trapped by the filter unit could attain 24.1 kg. The purification unit is suitable for complex working conditions of natural gas transmission and distribution such as high gas pressure fluctuations and high oil and water dust contents.