The aroma components of marjoram oil were analyzed by GC/MS, and the peak area normalization method was used to calculate the relative content of each component. With the mass spectrometry library search, 58 compounds which account for 95.61% in the aroma components of marjoram oil, were identified by using reference literature, retention index. The cis(trans)-isomers isomers were confirmed by using retention index, and the accuracy of compound qualitative analysis in natural flavor was improved. The aroma of the key aroma compositions of the marjoram oil (linalool, alpha-terpineol, 1,8-cineole, linalyl acetate, alpha pinene, beta-pinene, myrcene, camphene, beta-caryophyllene, sabinene, camphor, borneol, et al) was determined, and the results provided the technical support for the development and application of marjoram oil.