The chemical constituents of the essential oil from branches and leaves of Thuja koraiensis Nakai were analyzed by GC-MS-DC. 50 components were identified from 53 isolated components. Their content identified are 99. 16 % of the total amount. The main components are carvyl acetate (33. 37 % ) , fenchone ( 15. 73 % ) , thujanone (11. 28%), sabinene (8. 23%). 4-terpineol (5. 1 3%) , etc. It proved that the essential oil of this species is to develope as an edible and medicinal perfume material.