The invention provides a sewage treatment method. The method comprises the steps that anaerobic treatment, aerobic biochemical treatment and sedimentation treatment are sequentially performed on sewage; the sewage processed through sedimentation treatment enters a coagulation reaction pool; the sewage flowing through the coagulation reaction pool enters a ceramic membrane filter; the sewage flowing through the ceramic membrane filter enters an ozonic catalytic oxidation contact pool; the sewage flowing through the ozonic catalytic oxidation contact pool enters an activated carbon pool. According to the deep treatment technology method for the sewage generated in ethyl alcohol preparation through cassava, effluent can meet the first-class A standards of 'integrated wastewater discharge standard' (GB8979-1996), and the COD concentration is lower than 100 mg/L. Accordingly, the deep treatment technology method for the sewage generated in ethyl alcohol preparation through the cassava is efficient, economical and stable.