Abstract: A novel nano-silica surface-modified by silane was used as a reinforcing filler for HTV (heat vulcanization) silicone rubber. The dispersion morphologies and network st ructure of the composites were analysed by scanning elect ronic microscopy (SEM) and Payne effect ; the crystal behavior at low temperature was studied by differential scanning calorimet ry(DSC) . And the effect of these fillers on the mechanical properties of silicone rubber was investigated. Because the surface of these nanoparticles was enwrapped by apolar methyl , they can disperse in therubber perfectly without adding any dispersant . The result s indicate that at respective optimum content , the catenarian nano-silica (DNS-3) has evidently better reinforcement to silicone rubber in the tensile st rength , tear st rengthand elongation at break than the silica nanoparticle synthesized by aerosol method (A-200) . The DNS-2 nano-silicahas a similar reinforcing effect to nanO₂silica compared with A-200 , but the gross rubber of the DNS-2 system wassof ter and has better processability than that of A-200.