Based on self-designed contact oxidation devices,the urban polluted river water was studied through the natural enrichment process of indigenous microorganisms.The removal effects of major pollutants,the varies of SS and VSS,biofilm and biological phase were discussed;Various factors which can affect biofilm colonization rate were analyzed;The judgment based on mature of biofilm was given.The compound biological purification was established through added special effect bacterium after the mature of biofilm,the removal effect of pollutants and some influence factors of treatment effect were analyzed.COD and BOD5 removal rate of integrated system can reach to 90.8%、97.0% after normal operation.