Taking imidazole as primary substance,1-methyl-4,5-dinitroimidazole was synthesized in DMF by reaction of methyl suifate((CH₃)₂SO₄) with 4,5-dinitroimidazole obtained from nitration. Its structure was characterized by IR, elemental analysis, MS and ¹H NMR. The nitration mechanism of 4, 5-dinitroimidazole was analyzed. Results show that the yield of 1-methyl-4, 5-dinitroimidazole is 62%, and its melting point is 77 ℃. The optimum parameters are obtained: reaction temperature is 45-50 ℃, and reaction time is 4 h, the molar ratio of 4, 5-dinitroimidazole to (CH₃)₂SO₄ is 1:6. The pH value of 4, 5-dinitroimidazole (0.63 mol·L^-1 acetone solution) is raised from 3.74 to 6.77 of 1-methyl-4, 5-dinitroimidazole (0.63 mol·L^-1 acetone solution).