1-Methyl-3, 4, 5-trinitropyrazole (MTNP) was synthesized by one-step method using 1-methylprazole(1-MP) as raw materials and N₂O₅-oleum(20%) as nitrating agent. Its structure was characterized by IR, NMR, elemental analysis and MS. In addition, the influences of the mass fraction of N₂O₅, molar ratio of 1-MP and N₂O₅, reaction temperature and time on MTNP yield were studied. The optimum reaction conditions were obtained as: mass fraction of N₂O₅ 20%, n(1-MP):n(N₂O₅)=1:5, reaction temperature 165 ℃ and reaction time 1.5 h, respectively. Under such conditions, the yield of MTNP can reach up to 60.32%.