A novel exfoliated silicone rubber／clay nanocomposite has been synthesized by hydroxyl-terminated polydimethylsiloxane and organoclay．HTAB and TPAC were used as swelling agents to treat Na-montmorillonite for forming organoclay．The organoclay and nanocomposite were confirmed by X-ray diffraction (XRD)．The d-spacing in TPAC-mont is 4.96 nm

being larger than that of the HTAB-mont．The mechanical properties of the nanocomposites have been measured by tensile testing machine．The results proved that the nanometer-scale silicate layers of TPAC-mont were completely exfoliated in silicone rubber matrix in the cases of 1％ to 10％ TPAC-mont content．The nanocomposites exhibit markedly improved mechanical properties and thermal stability when compared with the pure polymer or conventional aerosilica-filled silicone rubber．A 200％～300％ increase in the tensile strength and a 100％ increase in the elongation at break were found for TPAC-mont／silicone rubber as compared to that of pure silicone rubber. The reinforing and intercalating mechanism of silicate layers in silicone rubber matrix were discussed．