In this study, we investigated the allelopathic effects of βcembrenediol and its phytotoxic mechanism on Arabidopsis thaliana seedlings. The results showed that: (1) βcembrenediol significantly reduced fresh weight of A. thaliana. The fresh weight of A. thaliana seedlings treated with the compound at high concentrations (50 μmol/L) was reduced more than 30% compared to the control; (2) After βcembrenediol treatment, the levels of chl a, b in A. thaliana leaves both declined in a concentrationdependent and timedependent manner;(3) βcembrenediol inhibited the activities of POD and SOD, while increased the content of MDA. These results indicated that under the stress of βcembrenediol, the activities of enzyme were inhibited and the degree of membrane lipid peroxidation was strengthened, and chlorophyll content was decreased, ultimately resulted in growth inhibition of A. thaliana seedlings.