The volatile components of clary sage oil were identified by gas chromatography/time-of-flight mass spectrometry (GC-TOFMS). The peak area normalization method was used to calculate the relative content of the components. With the MS library search, 32 compounds, which account for 91.24% in the volatile components of clary sage oil, were confirmed by using retention index. A rapid and effective GC-MS method for simultaneous determination of linalool, ambrox, and sclareolide in clary sage oil has been developed. Three samples were used for method evaluation. The relative standard deviations (RSD) were <4% for linalool, ambrox, and sclareolide. The limits of detections (LOD) were 80, 50, and 150 mu g L-1 for linalool, ambrox, and sclareolide, respectively. The recoveries were 90-109% for linalool, 91-105% for ambrox, and 94-103% for sclareolide. The method could be applied to measure linalool, ambrox, and sclareolide in clary sage oil.