In the present paper, the similar spectra of 18 samples, which include Astragalus, red-blue Astragalus and Codonopsis, were obtained in the range of 1 600～700 cm-1. The result showed that all kinds of herbs have their own characteristic similar spectra, and 18 samples can be identified according to the characteristic similar spectra. Furthermore, three correlation coefficients of 93 ganoderma samples were calculated which is in the range of 1 560~1 502, 1 460~1 421 and 1 319~1 260 cm-1 according to the information of similar spectrum of infrared spectrum of ganoderma. Without priori knowledge of the classification of these samples, the K-means cluster analysis can successfully divide them into four classes, i.e. Ganoderma lucidum and Ganoderma sinensis, Ganoderma atrum, Ganoderma aoshiba, Ganoderma multiplicatum. This result is consistent with the result of morphological classification.