Reactive dye BES golden yellow simulated wastewater was treated with H2O2-assisted photolysis method. Influences of factors such as reaction time, initial pH and H2O2 dosage were investigated, and the reaction kinetics of the process were explored. Results showed that, the degradation of 200 mg/L BES golden yellow solution happened only in the presence of both conditions: UV irradiation and H2O2 addition. Initial pH and H2O2 dosage had remarkable influence on the removal efficiency of the dye. Through several groups of univariate experiments, the optimum pH and H2O2 dosage of the photolysis process were found to be 6–7 and 0.0375 mL 30% H2O2 per milligram of BES golden yellow, respectively. The photolysis process was approximately in accordance with the second-order kinetic equation.