The nano-graphite powder was prepared by means of detonating of pure TNT(trinitrotoluene) explosives in a steel chamber. X-ray diffraction(XRD) and IR results indicate that the black solid powder which collected from the wall and the bottom of the chamber after the detonation has graphite structure and the average size of the particles of graphite is 1.86—2.58 nm. In the FTIR spectrum,there are two characteristic absorption peaks of graphite at 1 561 and 1 233 cm -1 and two antisymmetrical stretch vibration absorption peaks of CH2 at 2 923 and 2 853 cm -1 ,and one flexural vibration absorption peak of CH2 at 1 467 cm -1 . The vibration absorption peaks of CH2 disappeared when the nano-graphite is treated by acid. From the XRD spectrum and the mechanism of forming nano-graphite,the reason of the vibration absorption peaks of CH2 existing in the FTIR of nano-graphite was discussed. [WT5HZ]