The recent treatment scale of a sewage treatment plant in an chemical industry park is 4000m³/d . The industrial wastewater in the chemical industry park is treated by air flotation, fenton fluidized bed, hydrolytic acidification, improved A2/O biochemistry, high efficiency sedimentation tank, denitrification deep bed filter, catalytic ozone oxidation and other processes. The process flow, main design parameters and operation cost of each treatment unit are emphatically introduced. The actual operation results indicate: In stable operation stage, the averag concentrations of COD, NH₃??N , TN, TP and SS in effluent are 25.6, 1.1, 8.6, 0.23 and 8.5 mg/L, respectively and the average removal rales are 93.44%, 97.25%, 85.67%, 95.40% and 95.75%. Respectively, which are better than the standard of Municipal wastewater treatment plant I in Table1 of "Huaihe valley in Anhui Province emission standards for major water pollutants from urban sewage treatment plants and industrial industries" (exposure draft). It has good social and economic benefits, and can provide reference for other sewage treatment plant in an chemical industry.