Abstract: In order to extract flavonoids from Shaxi pomelo peel by the microwave method, Shaxi pomelo peel was taken as raw material, microwave power, the extraction time, ethanol concentration, ratio of material to liquid on the extraction rate of flavonoids were subjected to research. The optimal conditions for the extraction of flavonoids through L₉(3⁴)orthogonal experimental design are as follows: microwave power 250W, radiation time 2min, ethanol concentration 70%, ratio of solid to liquid 1:70. The extraction rate of flavonoids under the optimal conditions was 0.272%.