Abstract: Changes in material compositions of the shoots and roots of Astragalus sinicus treated with different concentration of selenium(Se)(0, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 and 5.0 mg·L^-1) were analyzed, using the fourier transform infrared spectrometry, two-dimensional infrared correlation spectroscopy and principal components analysis, in order to investigate variation of the chemical composition of A. sinicus in spectroscopy and microscopic dynamics relative to concentration of Se in treatment. Results show that the shoots and roots of A. sinicus did not change much in shape of their Se absorption peaks, but did quite obviously in absorbence, which indicates that concentration of Se did not affect much chemical composition of the plant, but did its content in the plant; The -OH, C-OH and C=O group absorption peaks in the roots and the C=O, -OH and -COO group absorption peaks in the shoots of the plant moved in location, indicating that concentration of Se in the soil had a significant effect on these groups in the plant, which shows that they may be closely related to the absorption, complexation, and transportation of Se in the plant. Within the band of 890-1750 cm^-1these groups in A. sinicus displayed a strong synergic effects or a strong interaction and varied sharply in two-dimensional infrared correlation spectroscopy, which indicates that the two-dimensional infrared correlation spectroscopy provides richer information about their structures, improves resolution of the spectra and captures dynamic changes in material system and molecular structure with changing Se concentration, and further on providing the study on mechanisms of plants tolerating heavy metal stress with an effective tool.