Abstract: A contain-grid type multiphase interface detection system used in oil/gas/water separater has been developed. The system can indicate the direct positions of the interfaces between water/emulsion, emulsion/oil and oil/gas, which can meet the needs of different oilfields. This system has changed the former way of the single object position detection. It adopts the parrallel electric capacity sensor series in coulometric detection, which offers higher accuracy in interface detection. The whole system is compact structune, easy to manufacture and has stable working performance.