Abstract：The functionalised mesoporous molecular sieves were prepared by using 3-aminopropyltriethoxysilane (AM) to react with calcined pure siliceous SBA-3. By means of XRD, TEM, N_2 adsorption-desorption isotherms, FT-IR and UV-vis diffuse reflectance spectroscopy of adsorbed Relchardt's dye, the structure, the pore properties and the polarity on surface of the functionalised samples were characterized. It is shown that the hexagonal structural character is mostly retained after the functionalization. The population of silanol groups on the surface greatly decreases due to being consumed in the reaction with organosilane, resulting in a reduction in surface polarity. In addition, the pore volumes, surface areas and pore diameters of the functionalised samples decrease since the space within channels are partially occupied by the functional molecules.