3-Amino-4-nitrofurazan(ANF) was successfully synthesized from 3,4-diamino-furazan(DAF) by an improved method. In the synthesis,oxalic acid was employed with sodium tungstate as a cocatalyst instead of sulfuric acid,and 30% H₂O₂ was employed as the oxider instead of 50% H₂O₂. The effects of reaction temperature,reaction time and quantity of catalyst on the conversion of DAF to ANF was studied by orthogonal design. The optimal reaction conditions were obtained as follows: reaction temperature 30 ℃,reaction time 6 h,the mole ratio of cocatalyst to DAF 1：1. The conversion of DAF was about 33.70% under the optimal reaction conditions.