Fourier transform infrared spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy was used to identify the different parts of Danggui in this paper. Guitou and Guiwei are two parts of the same officinal plant, and similar to each other in normal. FTIR spectra revealed the comparabilities of these two parts in herbal characters, organizing structure and alkaloid components. However, variance in amino acids and naphtha contents, which is aroused by the different parts of the angelica, could be identified easily and clearly in 2D FTIR spectra. Thus the fast and accurate property of 2D FTIR spectroscopy makes it a powerful and new approach to evaluating the medicinal herbs impersonally.