Abstract: 5-Aminotetrazole trinitrophloroglucinolate ((ATZ) TNPG) was prepared and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray diffraction analysis and it belonged to orthorhombic systemand Pbca space group with a=0.6624(2) nm, b=1.7933(4) nm, c=2.3117(5) nm, V=2.7458(9) nm3, Z=4, and Dc=1.849 g·cm-3. The molecular formula was confirmed to be (ATZ)TNPG·2H2O. 5-Aminotetrazole cation (ATZ+) and trinitrophloroglucinol anion (TNPG-) were linked into 2-Dlayers along b-axis and c-axis by hydrogen bonds. Then the layers were linked along a-axis by hydrogen bonds between the water molecules belonging to different layers. The thermal decomposition mechanism of the compound was studied by differential scanning calorimetry (DSC), thermogravimetry-thermogravimetric analysis (TG-DTG), and Fourier transform-infrared (FT-IR) spectroscopy techniques. Under nitrogen atmosphere with a heating rate of 10 ℃·min-1, the compound experienced one endothermic process with peak temperature of 76 ℃ and one exothermal process with peak temperature of 203 ℃. The former was confirmed to be a dehydrate process. The latter was the decomposition of TNPG- and ATZ+ in the compound. The exothermic enthalpy change of this process was -212.10 kJ·mol-1. The kinetic parameter calculation from Kissinger’s method were, E=132.1 kJ·mol-1, ln (A/s-1)=12.54 with r=0.9990, and the calculation results from Ozawa-Doyle’s method were, E=133.1 kJ·mol-1 with r=0.9992.