Abstract: To decompose and transform the toxic nonbiodegradable organic compounds of ABS resin wastewater and increase its biodegradablity,three different chemical oxidation methods are used.Influences of the different chemical oxidation methods on biodegradation and removal efficiency of COD,TOC,TN and benzene series are investigated.Resultsshow that toxic nonbiodegradable organic compounds can be directly mineralized by fenton reagent,the removal efficiencies of COD,TOC,TN and benzene series are 70.6%,77.7%,36.0%,and 100%,respectively,and then ρ(BOD₅)/ρ(COD) increases from 0.32 to 0.56.The organic compounds can be transformed into biodegradable organic compounds by ozonation,the rate of decomposing and transforming of benzene series reaches 100%,and the transformation efficiency of NH₃-N from organic nitriles is 58.9%;therefore,ρ(BOD₅)/ρ(COD) increases from 0.32 to 0.51.The treatment effect of sodium hypochlorite is the worst,and the more toxic of the chlorinated compounds may be produced,which causes ρ(BOD₅)/ρ(COD) to reduce to 0.29.