Single factor and L₉ (3⁴) orthogonal experiments were conducted to evaluate the effect of ethanol concentration, the liquid-solid ratio, and microwave power, extraction time on extraction yield of flavonoids from Osmamthus fragrans var. thunbergii flowers. The results show that the factors affecting microwave-assisted extraction yield of the flavones is extraction time, liquid-solid ratio, ethanol concentration, and microwave power in sequence. The optimum microwave -assisted extraction conditions are as follows: ethanol concentration of 50%, the liquid-solid ratio of 1︰35(m︰V), extraction time of 8×20 s and microwave power of 300 W, and the extraction rate under this condition is 20.30%.