Abstract: To investigate the optimal extraction conditions of monoterpene glycosides from seed cake of Paeonia ostii under ultrasonic assistance, three extraction parameters including ultrasonic time, ethanol concentration and liquid/material ratio on the extraction rate of monoterpene glycosides were optimized. On the basis of single factor tests, the extraction technology of monoterpene glycosides from the seed cake of Paeonia ostii was optimized by response surface methodology. The optimum conditions obtained were as follows:extraction time was 35 min, ethanol concentration was 41%, liquid/material ratio was 35∶1 (m L/g) . Under this conditions, the extraction rate values of monoterpene glycosides was 7.089%.