Hydroxylammonium 2-dinitromethyl-5-nitrotetrazolate (HADNMNT) was synthesized via neutralization reaction with hydroxylamine, using 2-dinitromethyl-5-nitrotetrazole (HDNMNT) as raw material. Its structure was characterized by FTIR, ¹H NMR, ¹³C NMR, ¹⁵N NMR and elemental analysis. The thermal stability of HADNMNT was studied by DSC. The detonation velocity and detonation pressure of HADNMNT were calculated by a density function theory and K-J equation. The theoretical specific impulse of monopropellant HADNMNT was calculated by the principle of minimum free energy under the standard state(pressure is 68.9 MPa, expansion ratio is 70:1). Results show that the yield of HADNMNT is 98.4%, and the peak temperature of DSC curve at a heating rate of 10 ℃·min^-1 is 145.3 ℃. Its detonation velocity, detonation pressure and specific impulse are 9.240 km·s^-1, 39.54 GPa and 2639.8 N·s·kg^-1, respectively.