2,6-Diamino-3,5-dinitropyridine-1-oxide (ANPyO) was synthesized with 2,6-diaminopyridine as a starting material by acetylation, N-oxidation, nitration and hydrolysis steps in turn, and the yield of ANPyO was up to 81%. The main factors affecting the acetylation, N-oxidation and nitration were investigated, and the structures of intermediates and ANPyO were characterized by ¹H NMR,MS and IR spectra.