To get the crystal structure of 1-trinitromethyl-3-nitro-1, 2, 4-triazole(TNMNT) and estimate its properties, using 3-nitro-1, 2, 4-triazole as starting material, TNMNT was synthesized via substitution reaction and nitration reaction with total yield of 62%. The pure single crystal of TNMNT was cultured and obtained by solvent evaporation method using absolute ethyl alcohol as solvent. Its structure was characterized by NMR spectrometry, IR spectrometry, and single crystal X-ray diffractometer. The thermal stability was analyzed by the DSC-TG method. The enthalpy of formation and detonation parameters were calculated with Gaussian 09 and EXPLO5(V6.02) program, respectively. Results show that the crystal of TNMNT belongs to monoclinic system, space group is P21/c with crystal parameters of a=6.643(3)Å, b=20.494(7)Å, c=6.698(3)Å, β=94.225(9)°, V=909.4(6)Å, Z=4, D_c=1.922 g·cm^-3, μ=0.190 mm^-1, F(000)=528.0. The thermal decomposition peak temperature of TNMNT at a heating rate of 5 ℃·min^-1 is 158.3 ℃. Its standard enthalpy of formation is 210.9 kJ·mol^-1, detonation velocity 9023 m·s^-1, and detonation pressure 35.5 GPa. The existence of numerous intermolecular and intramolecular hydrogen bonds makes the TNMNT molecule stably exist, and the introduction of the trinitromethyl moeity makes the energy of TNMNT molecule enhance.