Abstract：2-Chloro-4,6-di(3-triethoxysiloxy-1-aminoproply)-1,3,5-triazine(3) was prepared by substitution reaction of cyanuric chloride with γ-aminopropyl triethoxysilane. A novel halogen-free and high silicon content of charring agent(5) was synthesized by reaction of 3 with diethylenetriamine(4). The structure and thermal properties were characterized by 1H NMR, FT-IR and TGA. Effects of molar ratio of raw materials, acid-blinding agent, reaction time, reaction solvent and reaction temperature on the yield of 5 were investigated. The optimum reaction conditions were as followed: toluene was solvent, triethylamine was acid-binding agent, and n(3) : n(4) was 3.3:1, at 100 ℃ for 11 h, the yield was 62.7%. The initial decomposition temperature of 5 was 197 ℃, and the char yield was about 36.7% at 700 ℃.