By means of prefractionation on a silicagel column and combination of GC-Mass spectrometry, the essential oil constituents of Thymus magnus Nakai were analysed. Ten terpenoid compounds, ${gamma}-terpinene$, ${alpha}-pinene$, ${eta}-caryophyllene$, ${eta}-bisabolene$, pcymene, 4-isopropyltropolone, thymol, carvacrol, terpinen-4-ol and Borneol, were identified by referring to the spectrums of their authentic specimens.