To analyze and identify the Dendrobium officinale Kimura et Migo., Dendrobium nobile Lindl. and Dendrobium chrysotoxum Lindl. as well as their two extracts by using the Fourier transform infrared spectroscopy (FTIR). Fourier transform infrared spectroscopy (FTIR) was used to analyze and identify the structures of Dendrobium officinale Kimura et Migo., Dendrobium nobile Lindl., and Dendrobium chrysotoxum Lindl. as well as their extracts. The structural information of samples showed that all the Dendrobium officinale Kimura et Migo., Dendrobium nobile Lindl., and Dendrobium chrysotoxum Lindl. contained the characteristic absorption peaks in the range of 2 920, 2 852, 1 737 and 1 509 cm-1. Additionally, the presence of characteristic absorption peaks in the range of 1 000～1 200 cm-1 presumed that lipids, aromatics and starches were contained in all of these three Dendrobium samples. The above results were confirmed by the secondary derivative infrared spectra (SD-IR). In addition, according to the peak strength determine the difference in compound content contained in the three kinds of Dendrobium, and the secondary derivative infrared spectra also showed that the contents of lipids and starches were higher in the Dendrobium officinale Kimura et Migo. and Dendrobium nobile Lindl. than those in the Dendrobium chrysotoxum Lindl.. The content of lipids in the Dendrobium nobile Lindl. and the content of polysaccharides in the Dendrobium officinale Kimura et Migo were higher than those in the other two samples. Meanwhile, the characteristic absorption peaks of the calcium oxalate at 1 318 and 782 cm-1 were observed in the secondary derivative infrared spectra (SD-IR). The component and content of both two extracts were different from each corresponding samples, and the differences of peak shape, peak location and peak strength in different Dendrobium samples were also observed. The characteristic absorption peaks of lipids, aromatics and polysaccharides were observed in both water extraction and alcohol precipitation extract and anhydrous ethanol extract. Further comparison with the standard substance indicated that the main polysaccharides in Dendrobium nobile Lindl., and Dendrobium chrysotoxum Lindl. were starches which were mucopolysaccharide in Dendrobium officinale Kimura et Migo. The lipide and aromatic series were confirmed by infrared spectrum, and the aromatic series in the Dendrobium chrysotoxum Lindl was higher. Integral structure analysis based on infrared spectrum contributed to the identification of differences in the Dendrobium officinale Kimura et Migo., Dendrobium nobile Lindl., and Dendrobium chrysotoxum Lindl. The method is suitable to be used for rapid identification, quality evaluation and control for various cultivars, which provides the foundation for systemic identification of Dendrobium.