Abstract: The Fe-silicon nitride synthesized by flashing combustion process was studied to determine the reaction temperature between Fe and silicon nitride, the account of N₂ given out in the course of the reaction, and the change of the microstructure during calcination. The results showed that at 1127.2℃ the Fe-silicon nitride self-reacts and releases N₂ and under 101.3 kPa the volume of N₂ given out in the course of the reaction is 20 times more than that of the starting material. N₂ is produced quickly, and completes in several decade seconds. With the producing of N₂, the structure of Silicon Nitride around Fe becomes loose and porous, or cracks are formed by the reaction between Fe and silicon nitride. So if it is made use of that Fe-silicon nitride self-producing N₂ at the high temperature, the performance of the material on a base of Fe-silicon nitride could be greatly improved.