Objective:To analyze the chemical composition of the essential oil of Radix Aucklandiae and investigate it's influence on platelet aggregation induced by ADP.Methods:The essential oil was extracted from Radix Aucklandiae by steam distillation

and then an analysis was conducted by applying GC-MS(capillary gas chromatography-mass spectrometer)

and investigated for the inhibitory effects on rabbit platelet aggregation in vitro.Results:The experiments showed that 59 components were identified

accounting for 72.91 percent of the total essential oil.The essential oil was mainly composed of dehydrocostuslactone、costunolide、cedrenol、α-elemene、1

3-cyclooctadiene、eudesmol、α-selinene、β-caryophyllene、(+)-longifolene、3

4-octadiene

7-methyl-etc.Among them Lactones like Dehydrocostuslactone and costunolide are essential components.Conclusions:Fifty nine components were identified in essential oil of Radix Aucklandiae by GC-MS.Volatile oil of Radix Aucklandiae dehydrocostuslactone and costunolide have obvious inhibiting effect on platelet aggregation induced by ADP.The bioactive components derived from terpenes and lanctones in oil of Radix Aucklandiae.