Abstract: AIM　To study the metabolite of β-elemene in the bile of rat. METHODS　After iv 100 mg.kg^-1 β-elemene, the metabolite in rat bile was extracted by ether. Mass spectrometry, nuclear magnetic resonance, infrared spectrometry and ultraviolet spectrometry were used to analyze the metabolite of iv β-elemene in rat bile. RESULTS　It was confirmed by nuclear magnetic resonance that the methyl of No.11 carbon connecting with No.10 carbon of a metabolite in rat bile was oxidized to be aldehyde. The molecular weight of the metabolite was 218 which detected by mass spectrometry. Infrared spectrometry and ultraviolet spectrometry proved that the aldehyde existed in the metabolite. The structure of the metabolite in bile of rat was identified, that was 1-methyl-1-ethenyl-2-isopropenyl-4-isopropenyl aldehydohexamethylene. CONCLUSION　The biotransformation of β-elemene exists in vivo.