Abstract:The chemical components of the two leaf essential oils from Ligu-sticum sinense Oliv. cv. Chuanxiong Hort. collected on March 20, 1986 and April 20, 1986 resp. were analyzed by GC and GC-MS-DS of 200-202 peaks isolated by a 50m x 0.25mm i. d. bonded methyl silicone fused silica glass column from the two oils, 44 common components were identified by comparing the obtained mass spectra and retention indices with those of mass spectral data base and with retention indices determined by Jennings, W. and by authentic sample superimpositions. The relative contents of the components were calculated by LCI -100 integrator with the peak area normalization method. The experimental results showed that differences between the two oils were mainly quantitative. Ligustilide (16.62%), one of the major and physiological active components of the oil collected on April 20, was detected in minor amounts (0.36%) in the oil collected on March 20, on the other hand, γ -pathoulene ( 18.34% ) , trans-β-farnesene (8.83%) which were the main components of March oil existed in small proportion (7.79% and 1.88% resp.) in April oil.