The chemical differences of panax notoginseng before and after processing were analyzed by Fourier transform Infrared spectroscopy (FTIR) combined with two-dimensionalcorrelation spectroscopy (2D-IR). Compared with conventional IR spectra of the samples, the FTIR spectra of panax notoginseng and its processed products were similar in the range of 1 200～400 cm-1. The difference was that prepared panax notoginseng had strong and characteristic peaks at 2 925, 2 855, 1 746, 1 460, 1 376 and 1 158 cm-1, which all arose from the characteristic vibration of peanut oil. This was because there was some peanut oil left in the panax notoginseng, when panax notoginseng after processing. Obvious differences were observed between 2D-IR spectra of them, in the range of 1 400～1 700 cm-1, there was only one auto peaks at 1 650 cm-1 in the spectra of panax notoginseng, but there were auto peaks at 1 469 and 1 640 cm-1 in the spectra of prepared panax notoginseng. In the range of 1 400～1 700 cm-1, the 2D-IR spectra of panax notoginseng and its processed product present characterstic peaks at 1 139(1 137), 1 194(1 196), 1 121(1 221)cm-1 respectively, but the relative intensities of auto peaks were changed. For example, auto peak around 1 139 cm-1 was enhanced, but auto peak around 1 194 cm-1 was weakened. The results of 2D-IR correlation spectroscopy indicated the decomposition of flavonoids, saccharides and saponins. This method can track dynamically the processingprocedure of panax notoginseng and reveal the main tansformations, so it can explain the pharmacology of panax notoginseng and its processed product by FTIR and 2D-IR.