Abstract: The problem of heavy loss of polymer solution viscosity because of hydrogen sulfide in crude sewage was studied. By optimizing hydraulic retention time and air/water ratio of air oxidation method, hydrogen sulfide was removed thoroughly and viscosity of polymer solution(the concentration was 1700 mg/L)was increased from 5 mPa·s to 30 mPa·s, and it had high thermal stability, which met the design requirement of polymer-surfactant displacement method. Meanwhile, the viscosity of polymer solution prepared by sewage after desulphurization processing(both mother liquid and dilution prepared by sewage)could reach more than 30 mPa·s, so a great quantity of freshwater and production cost could be saved.