In this work, the degradation of Rhodamine B by hydrogen peroxide under microwave irradiation is studied and the optimum conditions are designed by single factor experiment. The UV-VIS spectral changes of RhB solution is detected under the optimum conditions. The results indicate that microwave induction can efficiently improve the oxidative degradation of RhB by hydrogen peroxide in alkaline solution, espcially the dye has the best photodegradation efficiency more than 99% when the concentration of RhB was 300mg/l and the pH of solution was 12 after irradiated for 10min, It is better than RhB under visible irradiation in alkaline environment with hydrogen peroxide. The solution initial pH has no effect on the temporal absorption spectral of RhB. The process of reaction conforms to the first-order kinetic equation.