Abstract: Two kinds of silane coupling agents (KH550 and KH792) were applied to modify the surface of mesoporous molecular sieve MCM-41, and thus measurements including N₂ adsorption-desorption, FTIR and TGA etc, were employed to characterize. The MCM-41/epoxy composite was prepared by in-situ polymerization method and the influences of coupling agent kinds and MCM-41 content on curing process and properties of composite were explored. The results show that the silane coupling agent could react with silicon hydroxyl of MCM-41 surface and thus the functional group is grafted to the internal and external surface of molecular sieve. The specific surface area of surface modified MCM-41 decreases to the one fifth of neat MCM-41 and the KH550 grafting ratio on surface of MCM-41 is just half of that in KH792.The reaction between KH550 and MCM-41 external surface is more ample and KH792 has more sufficient modification effect on internal wall of MCM-41 pore channel. The curing kinetics results show higher reaction activity of KH792 containing functional groups of the primary and secondary amine but hindering the epoxy macromolecule move into pore channel and thus MCM-41 is added as spherical particle in epoxy while the epoxy macromolecule could move into KH550 surface modified MCM-41 pore channel forming the interpenetrating structure. KH550 surface modified system improves the storage modulus and glass transition temperature greatly because the character of porous effect appears and organic-inorganic interpenetrating structure composite system forms. The character of KH792 surface modified system shows the conventional spherical nano particle and thus storage modulus and glass transition temperature have slight improvement compared to pure epoxy.