Abstract: In order to explore the component difference between Hylocereus undlatus and Epiphyllum oxypetalum, fourier transform infrared spectroscopy（FTIR）, second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy（2D-IR）were analysed with their stems. The infrared spectrogram showed that there were five absorption peaks in stem of H undlatus, and four in E. oxypetalum; The similar peaks of both represent the same functional groups which were C—O—C（aliphatic hydrocarbon）、C—O—C、N—H、O—H（dimer）. But the differences were 1 041 cm^-1 H. undlatus, 1 077 cm^-1 H. undlatus, 1 033cm^-1 E. oxypetalum. The fourteen intensities absorptionpeaks was shown in stem of H. undlatus and sixteenin E. oxypetalum according to the second derivative infrared spectroscopy in the range of 667-1 866 cm^-1. An obvious characteristic peak was 955 cm^-1 in H. undlatus corresponded to the functional group of acid anhydride C—O, and 1 520 cm^-1 in E. oxypetalum corresponded to the functional group of amine N—H. There were same cross peaks between H. undlatus and E. oxypetalum,on map of 2D-IR spectroscopy in the range of 890-1 800 cm^-1 especially a strong positive cross peaks in the wave number of 1 321 cm^-1and 1 630 cm^-1, weaker positive cross peaks in the wave number of 1 046 cm^-1 &1 634 cm^-1 , 1 049 cm^-1 & 1 329 cm^-1, without negative cross peak.The positions of automatic spectrum peak was same with the fourier transform infrared spectroscopy（FTIR）on two-dimensional correlation infrared spectroscopy（2D-IR）.

Key words: Hylocereus undlatus, Epiphyllum oxypetalum, infrared spectrum, second derivative spectrometry, two-dimensional correlation spectroscopy