Based on the structure characteristics of miniaturization, portable, a non pressure-accumulated and handheld fire extinguishing bomb was designed, using hot aerosol to inject ultrafine powder. In order to achieve better gas driving force, at the same time inhibit the high temperature caused by hot aerosol, firstly gas generant was designed for charging. Secondly the experimental research on the gas generant performance was done for optimizing. Finally by the temperature test platform that was independently designed, the experimental research on the temperature change of the extinguishing agent at the outlet and handle was done. Experiments show that the performance of optimized gas generant is better, because the specific volume is bigger, 340ml/g, the combustion heat value is lower, 2920 J/g, and vacuum stability is better, 0.42ml/g; And safety of fire extinguishing bomb is better, because the highest temperature at the outlet is less than 60℃, and the highest temperature at the handle is less than 40℃.