AbstractDensity functional theory (DFT) is used to calculate and study the reaction mechanism of the four equations of nitrous oxide generation from plasticizer A3 (BDNPF: BDNPA=1 : 1). The optimal pathway is found for each equation, and finally, an optimal total pathway is found. At the same time, HONO is generated from A3 degradation. The stability is evaluated through ab‐initio molecular dynamics simulation (AIMD), and the electronic structure is analyzed to determine the active sites. The decomposition of A3 accelerates the aging of solid rocket propellant. Therefore, the mechanism of nitrous oxide generation from A3 can be revealed through various theoretical methods, which is of great significance for the subsequent slowing down of the aging of solid propellant.