Abstract: The three different silane coupling agents (methyltriethoxysilane (MTES), dimethyldiethoxysilane (DMDES) and trimethylethoxysilane (TMES)) were used to modify the surface of multi-walled carbon nanotubes (MWCNTs) under the hydrous conditions. The chemical structures of MWCNTs before and after modification were characterized by FTIR, XPS, TG and SEM. The different mass fractions of MWCNTs, MWCNTs-MTES, MWCNTs-DMDES and MWCNTs-TMES were filled in silicone rubber (SR). The MWCNTs/SR composites were prepared by mechanical blending. SEM images show that the silane modification can reduce the interaction between MWCNTs and improve their dispersion in SR. The tensile tests show that the interaction between MWCNTs and SR is enhanced and the compatibility between them is improved. The elastic modulus of the MWCNTs/SR composites shows no obvious change when the contents of modified MWCNTs are within 2wt%. The dielectric constant of MWCNTs/SR composite reaches 5.02 (at 10⁴ Hz) when filled with 2wt% modified MWCNTs-MTES, which is 57% higher than that of the pure SR, while the dielectric loss is still less than 0.01 (at 10⁴ Hz).