A combined approach of sub-window factor analysis and spectral correlative chromatography has been employed to analyze the constituents of essential oils of Dong quai. Essential oils are the main pharmacological active individuals of Dong quai. Some constituents in the main root of Dong quai have been identified by GC-MS with the help of sub-window factor analysis resolving two-dimensional original data into mass spectra and chromatograms. Correlative constituents in another part of the root fiber have been recognized by spectral correlative chromatography. Seventy six of 97 separated constituents in the essential oil of main root were identified and quantified, accounting for about 91.36% of the total content. Sixty seven correlative components in the essential oil of root fiber were recognized. The result proves that the combined approach is powerful enough for the analysis of complex herbal samples.