Abstract: Coumarin in teas was determined by GC/MS. The teas were extracted with dichloromethane using a sonicator, purified by a Silica column, and determined by GC/MS with selection ion monitoring mode. The result show that the calibration curve of coumarin is linear(R＝0.999 8) between 0.05 mg L^－1 and 4 mg L^－1. The precision is perfect(RSD=2.80％). The average recoveries are from 96.22% to 100.44%. The detection limit is 8 mg L^－1. The method is suitable for the quantitative analysis of coumarin in natural products.