Using 3,5-dichloropyridazine as starting material, 3,5-diamino-4,6-dinitropyridazine-1-oxide（DADNPO）and a new energetic compound 3,5-diamino-4-nitropyridazine-1-oxide（DANPO）were synthesized by substitution, oxidation, nitration and amination reactions. The structure of products and their intermediates were characterized by IR spectra, ¹H NMR, ¹³C NMR and elemental analysis. The effects of nitrification conditions on the purity and yield of nitrification were studied. The results show that the best nitration reagent of synthesized 3,5-dimethoxy-4,6-dinitropyridazine-1-oxide is nitric acid and sulfuric acid, the reaction temperature is 50~55 ℃, and the reaction time is 15 h. The detonation properties of DADNPO and DANPO were calculated by Gaussian 09 program and Kamlet-Jacobs formula. The results show that the detonation velocities are 8.486 km·s^-1and 7.224 km·s^-1, and the detonation pressures are 30.2 GPa and 23.09 GPa, respectively. Meanwhile, the thermal behaviors of two compounds were studied with differential scanning calorimetry (DSC). The exothermic decomposition peak temperatures of DADNPO and DANPO are 244.4 ℃ and 325.2 ℃ respectively, indicating that DANPO has better thermal stability than DADNPO.