Abstract:1-methyl-4-hydroxymethyl-1-silicone miscellaneous-4-phosphorus miscellaneous-2,6,7 -trioxabicyclo[2,2,2]-octane quaternary phosphonium sulfate,a kind of cage-shaped organosilyl quaternary phosphonium as flame retardant antistatic agent was synthesised by methyl trichlorosilane react with tetrakis hydroxymetyl phosphonium sulfuric. We discuss the impact of the reaction temperature、reaction time and resolvent on the yield, and we designed a new production route, which is the molar ratio of methyl trichlorosilane and tetrakis hydroxymetyl phosphonium sulfuric was 2:1, the reaction time was 8h at 120℃,and diethylene glycol dimethyl ether was used as solvent.The synthesized compound has been ascertained by FTIR、1H-NMR.DTA、Limiting oxygen index and surface resistance were used to characterize the performance of the final product. Further research of the product shows the decomposition temperature is 478.5℃, which has excellent flame retardant antistatic performance in the application tests.