2,6,8,12-Tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane (TNH₂IW) was synthesized from 2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (TAIW) by protection, nitration and deprotection. TNH2IW could also been obtained by reduction of hexanitrohexaazaisowurtzitane (HNIW, CL-20) with SnCl₂. The molecular geometries, electric structures, and thermodynamic properties of TNH₂IW were calculated using the density functional theory (DFT) method at the B3LYP/6-31G* level. The thermodynamic parameters including heat capacities and entropies were calculated, and also the polynomial functions between thermodynamic parameters and temperature were determined. The accurate heat of formation 461 kJ·mol^-1 of TNH₂IW in gas phase was obtained via designed isodesmic reaction in which the cage and the nitro group have been kept. The data obtained from the present study show a satisfactory detonation performance, with detonation velocity of 9.13 km·s^-1 and detonation pressure of 38.9 GPa, both of which are higher than those of TNT and RDX, not worse than those of HMX counterparts.