Abstract: This paper introduces the status of research on deep treatment of injection water and experimental study on application of ceramic filtration unit in deep treatment of injection water and underground water.Experiment re-sults show that injection water and underground water,first treated with conventional filtrating methods and then with ceramic filtration unit,have an oil content below5mg /l and suspended solid(grain diameter<1μm)content under1mg /l.The main indexes of water quality meet the requirements of Class A1standards in the″Proposed in-jection water quality indexes in clastic reservoirs and analytical methods″.