Based on the regulating of nanostructure on the properties of materials, the nanostructure of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was constructed by solvent/non-solvent method. Through strong nonsolvent effect and temperature effect,the keel-like nanostructure TATB was prepared.The microstructure of the sample was observed by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) and the crystal phase and particle size distribution of the sample were measured by X-ray diffraction (XRD) and Laser Particle Size Analyzer. The results show that the whole morphology of obtained sample is keel-like crystalline. And the crystal form does not change compared with the raw material and the size distribution is from 70 to 400 nm. The thermal analyses at different heating rates show that the thermal decomposition peak temperature of keel-like nanostructure TATB is 1.54-2.91 ℃ earlier than that of raw TATB, the apparent activation energy(E_a) is increased by 0.29 kJ·mol^-1, and the sensitivity to thermal stimulation is decreased. The thermal decomposition mechanism of keel-like nanostructure TATB obtained by differential method calculationis random nucleation (a core for a particle), whereas the raw material is three-dimension diffusion and its kinetic equation is Jander equation with sphericalsymmetry.