In this article, preparation of nano-graphite powder in steel chamber by using pure TNT ( trinitrotoluene )explosives has been introduced. X-ray Diffraction (XRD) results indicate that the black solid powder which collected from the wall and the bottom of the chamber after detonation has graphite structure and the average size of the particles of graphite is 1.86 nm~2.58 nm. Transmission electron microscopy (TEM) and micro-Raman spectroscopy confirmed that the black powder is hexagonal-graphite structure and its shape is ball or ellipsoid. Small angle X-ray Scattering (SAXRS) results revealed that the particle size of nano-graphite is 1 nm~60 nm.