A 1，3，5-trinitrobenzene /1，4-dinitroimidazole （TNB/1，4-DNI） cocrystal explosive was prepared by solvent evaporation. The crystal structure was characterized by single crystal X-ray diffraction analysis. Results shows that the cocrystal crystallizes in the orthorhombic space group P2₁2₁2₁ with crystal parameters of a = 6.4068（5） Å，b = 10.4569（8） Å， c = 20.7164（17） Å， α = β = γ = 90°， ρ = 1.776 g·cm^-3， Z = 4. The differential scanning calorimetry （DSC） was used to analyze the thermal properties of the TNB/1，4-DNI cocrystal explosive. The melting point is 84.4 ℃， which is significantly lower than that of both TNB （123.5 ℃） and 1，4-DNI （91 ℃）. The TNB/1，4-DNI cocrystal explosive can be re-formed into pure cocrystal explosive after melting and cooling. The detonation velocity and pressure of TNB/1，4-DNI cocrystal explosive were also calculated to be 7704 m·s^-1 and 26.08 GPa by the empirical nitrogen equivalent equations， which are significantly higher than those of the commonly used melt-cast explosive TNT. Therefore， TNB/1，4-DNI cocrystal explosive could be used as a new type of melt-cast explosive.