Crystalline structures of TATB including molecule structures, lattice parameters, band structures, XRD spectrums, total densities of states (DOS) and spatial distributions of charge densities at high pressures such as 0.1 GPa, 1 GPa, 10 GPa, 100 GPa, 1000 GPa are investigated by CASTEP in Material Studio, and the results show that: (1) TATB crystal cell mainly changes on c-axis orientation, and the energetic band structure of crystal and TATB molecular structure change a little when the pressure changes from 0.1GPa to 10GPa. (2) TATB can be compressed to get a density over 2.5 g cm-3 at tens GPa, and the total energy of the crystal doesn't increase much more. (3) TATB crystal exists as semiconductor at 0.1-100 GPa, and a transition from semiconductor to conductor is predicted at hundreds GPa, and TATB molecular structure must be destroyed at same pressure.