Abstract: As a new efficient separation equipment, supersonic separator has incomparable efficiency and economy with respect to traditional separation methods and equipments. In this paper, the numerical simulation between traditional supersonic separator and recycling separator with same structure and size were compared. Under the same outlet pressure, the flow distributions in the recycling separator was better than the former, the shock wave was further away from the throat which could expand the area of supersonic flow and improve the efficiency of gas-liquid separation. While the stability of flow influenced by the different inlet position of recycling chamber was analyzed, and the result showed that flow stability was better and could improve the separation performance when the inlet position was at the outlet of Laval nozzle.