A new refining process of 2,6-diamino-3,5-dinitropyridie-1-oxide(ANPyO) was investigated including acylation, recrystallization and deprotection procedures. The influence of different processing conditions on product purity, particle size distribution, impact sensitivity, friction sensitivity and micro-structure were studied and compared with that of refining method with CF₃COOH. Results show that the optimal conditions of new refining method are as following: DMF as solvent for the recrystallization of the intermediate (2,6-diacetamino-3,5-dinitropyridine-1-oxide) and ammonia as the amination agent and amination temperature 50 ℃. Under the conditions, ANPyO was prepared with yield of 90.5%, and the purity of 99.5%. Its properties were characterized with pH of 6.3, melting point of 355 ℃, vacuum stability of 0.01 mL·g^-1, impact sensitivity of 257 cm, friction sensitivity of 2%.