Abstract: An ultrasonic assisted method was used to study the optimum extraction of flavonoids in Miscanthus. The determined optimal extraction conditions of flavonoids were as follows:70% ethanol concentration, 1:30 ratio of raw material to liquid, 70℃ extraction temperature, 40 min extraction time, and three extract series, respectively. Under these conditions, total flavonoid content of M.lutarioriparius was 7.24 mg/g. The experimental yields of flavonoids from various kinds of M.sinensis were significantly different, ranging from 4.16 mg/g to 7.84 mg/g. The volatile oil components in Miscanthus x giganteus (hexaploid),‘GMG121’, and M.sinensis hybrid were determined by GC/MS, with 28 different components identified. This study provides useful information on genetic breeding, which has great significance for the development and utilization of M.sinensis.