Synthesization of 1H,1H,2H,2H-Perfluorooctyltrimethoxysilane through solvent-free hydrosilylation of 1H,1H,2H-perfluoro-1-octene with trimethoxysilane was efficiently conducted over the RuCl3·3H2O catalyst. The synergistic action of Ru3+ as the active center and the strong electronegativity of Cl to attract the electron of the electron-donating group –OCH3 in trimethoxysilane, activated the Si-H and thus promoted the reaction. The influences of different reaction conditions including feed order, feed ratio, catalyst dosage, reaction temperature and reaction time on the reaction yield were fully investigated, to conclude the optimized condition to achieve a yield of 86.80% was the feed of 1.2 mol trimethoxysilane per mole of 1H,1H,2H-perfluoro-1-octene, together with the addition of 9.56 × 10-4 mol RuCl3· 3H2O per mole of trimethoxysilane, at 80℃ for 4 h; while the additive of CuCl to RuCl3· 3H2O catalyst could further improve the reaction yield at 50℃. Finally, after understanding the activity of Ru with different valence state, the reaction mechanism was also proposed.