Abstract: In order to effectively control the pests in stored tobacco leaves,new botanical protectants were studied and developed.The activities of essential oil and isolated components of Platycladus orientalis were tested via fumigation and contact toxicity assays,and the chemical components in the essential oil were analyzed by GC/MS.The results showed that:1) A total of 34 components were identified in the essential oil,which accounted for 93.28% of total components;and the major components were α-pinene(15.08%),cedrol(12.63%),3-carene(9.68%) and caryophyllene(9.02%).2) By means of bioactivity screening,the essential oil possessed potential contact toxicity against Lasioderma serricorne(LD₅₀=50.45 μ g/adult) and Tribolium castaneum(LD₅₀=48.59 μ g/adult),and it also possessed fumigation toxicity against Lasioderma serricorne(LC₅₀=145.40 mg/L) and Tribolium castaneum(LC₅₀=39.25 mg/L).3) Three active components,α-pinene,β-phellandrene and 4-terpinenol,were obtained from the essential oil.It was proved that the essential oil of Platycladus orientalis and its active isolated components possessed certain contact and fumigation toxic activities against Lasioderma serricorne and Tribolium castaneum.