1-Amino-3, 5-dinitropyrazole (ADNP) was synthesized using 3, 5-dinitropyrazole as raw material and 2, 4, 6-trimethylbenzenesulfonic hydroxylamine (MSH) as aminating agent with a yield of 60.7%. Its structure was characterized by IR, NMR, MS and element analyses. The single crystal was cultivated in ethanol. Its single crystal structure was determined by a four-circle X-ray diffractometer. Its thermal properties were studied by TG-DSC. Results show that the crystal is orthorhombic, space group P2 (1)/n with crystal parameters of a=5.543(2)Å, b=9.866(4)Å, c=11.745(5)Å, Z=4, D_c=1.79 g·cm^-3, V=642.3(4)ų. Thermal analyses demonstrate that there is a sharp mass loss process from 170 ℃ to 266 ℃ with 99.1% mass loss. The two endothermic peaks temperatures appear at 110 ℃ and 264 ℃.