Abstract: Thujopsanone was synthesized by oxidation reaction with thujopsene as raw material, dichloromethane as solvent, methyltrioxorhenium(MTO) as catalyst, 30% H₂O₂ as oxidant, and 3-methylpyrazole as co-catalyst. The effects of reaction conditions on the oxidation were studied. The optimized reaction were obtained as follows: the reaction temperature 30℃, the molar ratio of raw materals(n(H₂O₂): n(thujopsene)) 1:1, the reaction time 3 h, the catalyst amounts 0.3%(based on the weight of thujopsene, similarly hereinafter), the dosage of 3-methylpyrazole is 10%. Under these conditions, the yield of thujopsanone was 72.1%, and the conversion rate of thujopsene was 97.3%. The structure of the products was identified by GC-MS and FT-IR, and it was confirmed as wasthujopsanone.