Hydro-fluoro-carbons (HFCs) gas fire extinguishing agents, such as trifluoromethane (CHF3), pentafluoroethane (C2HF5), hexafluoropropane(C3H2F6) and heptafluoropropane (C3HF7) is the most efficient Halon alternatives, which possess the properties of high fire-fighting efficiency, reliable performance, no residue after finishing their duty. The four kinds of fluorine-containing fire extinguishing agents will produce the toxic gas HF during the fire extinguish process. The fluorine-containing free radicals resulted from the thermal decomposition of HFCs reacts with H, OH and O radicals in the flame to prevent the chemical chain reaction in the process of the combustion. The amount of HF produced could be reduced by shortening the time to reach the fire extinguishing concentration, reducing the time of interaction between fire extinguishing agent and flame, and adding additives or inhibitor. Future work should gain deep insight into studying the chemical extinguishing mechanism under different usage conditions, and obtaining a lot of real data, such as the extinguishing concentration, the toxicity, the compatibility and corrosion of such HFCs fire extinguishing agents. It provides theoretical basis and application for reducing the release of toxic gas HF, expanding the application field, and developing some new type of HFCs fire extinguishing agents with better performance.