Abstract: Ultrasonic was employed to extract flavonoids from Pinus massoniana. Conditions for extraction were influenced by some factors, such as ethanol concentration,time and liquid-material ration, so they were optimized by response surface. Experimental results show the best conditions are as follows: the extracting time is 56 minutes,ethanol concentration is 40%, liquidmaterial ration equals 1:20, when the yield of flavonoids is 1.59%.This method is feasible for exploiting the material, and it provides the basis for its utilization. In the Response Surface experiment, compared with the factors of liquid-material ration and extracting time,ethanol concentration and power have greater influence on the extraction.

Key words: Pinus massoniana; ultrasonic extraction; flavonoids; response surface optimization