Using ethyl 2-(3-(dinitromethyl)-1H-1,2,4-triazol-5-yl)acetate as a starting material, diguanylurea 3,5-bis(dinitromethyl)-1,2,4-triazolate (DMDNMT) was firstly designed and synthesized via the reactions of nitration, hydrolysis and metathesis. The structures of all compounds were characterized by ¹H NMR, ¹³C NMR, IR and element analysis. Based on the theoretical values of densities and heat of formation, the detonation parameters were calculated using Gaussian 09 program and EXPLO5 6.04. Results show that the density of DMDNMT is 1.81 g·cm^-3, the heat of formation is -446.1 kJ·mol^-1, the detonation velocity and detonation pressure are 8624.8 m·s^-1 and 29.2 GPa, respectively. DSC and TG-DTG measurements indicate that the decomposition temperature of DMDNMT is 177.3 ℃, and its impact sensitivity determined by standard BAM method is 24 J.