To reduce the acidity of 3-nitro-1, 2, 4-triazol-5-one(NTO), a new energetic ionic compound guanylurea salt of 3-nitro-1, 2, 4-triazol-5-one(GUNTO) was designed and synthesized by two methods of a pot method and distribution method using guanylurea hydrochloride and NTO as starting material with total of yields over 85%.Its structure was characterized by IR, NMR, MS, elemental analysis and X-ray single crystal diffraction. The physiochemical properties and detonation parameters of GUNTO were studied. Results show that by the real density of 1.72 g·cm^-3 and the calculated enthalpy of formation of -347.35 kJ·mol^-1, the theoretical detonation velocity and detonation pressure predicted by the Kamlet formulas are 6683.49 m·s^-1 and 19.27 GPa, respectively. The mechanical sensitivities are determined as: the impact sensitivity is 0%, friction sensitivity is 0% and characteristic drop height of impact sensitivity H₅₀ is more than 125.8 cm. The peak temperature of DSC curve at 10 ℃·min^-1 is 236.8 ℃. In comparison with other amine salts of NTO, GUNTO has higher nitrogen content, better thermal stability and lower sensitivity.