A method for degrading artificial sweeteners from sewage, the method including: 1) introducing sewage to a secondary sedimentation tank and precipitating sediments; 2) collecting a supernatant from the secondary sedimentation tank, adding a NaOH solution or a perchloric acid solution to regulate the pH; adding an H2O2 solution to the supernatant to adjust a ratio of a molar concentration of H2O2 to a molar concentration of the sweetener in the resulting mixed solution to be between 1:1 and 30:1; transferring the resulting mixed solution to a photoreactor, irradiating the mixed solution by ultraviolet light, and stirring the mixed solution for between 5 and 30 min; and adding a 1.5% w/w aqueous NaNO2 solution to the mixed solution; and 3) collecting and analyzing an effluent obtained from 2), contacting the effluent with ClO2 for reaction in a disinfecting tank, and discharging the product.