Organic inorganic hybrid flame retardant materials were prepared via sol gel method using silica fume, polyacrylamide（PAM）, sodium silicate and KOH as raw materials which were used as exterior insulation materials. The material was characterized by FTIR, SEM and DSC and other modern analysis methods, its reaction mechanism was proposed. Results show that the PAM with partial hydrolysis reacts with ≡Si—O— chain derived from silica fume under alkaline condition, and a denser siliceous layer structure is formed, it can transform into material with lamellar structure during the combustion process, which produces heat shielding effect and improves the flame retardant performance, the appropriate amount of PAM can improve the flame retardant performance, cause its limit oxygen index (LOI) to reach 35.5% (by volume) with a flame retardant level of UL 94 V1 level.