Carbon nanotubes (CNTs) have been widely known as an excellent material for the assembly of nano-devices because they have many advantages that are extraordinary mechanical, thermal, electrical, and optical properties. Silica-coated CNT, which is composed of a CNT coated with a silica layer, has been reported as the first thermally conductive, mechanically strength improving, and electrically insulating filler. Therefore, silica-coated CNT composite are of interest because they are useful for the advancement of nanoscale sensors and electric devices. In this study, the silica coating process was performed through a sol-gel reaction of tetraethyl orthosilicate (TEOS) in ethanol at room temperature. During the sol-gel process, an amphiphilic polymer was used to increase affinity between silica and CNTs. In addition, the amount of TEOS was changed to optimize the amount of silica coated on the MWCNTs. The coating mechanism consisted of the physical adsorption of amphiphilic polymer onto the MWCNTs and the chemical coating of amphiphilic polymer-assisted MWCNTs with silica conducted under basic conditions. Due to strong interaction between basically modified CNTs and acidic TEOS, hard silica shell with a controllable uniform thickness was achieved. The silica-coated MWCNTs filled Poly(dimethyl siloxane) showed improved thermal conductivity and electrical resistivity. The silica-coated MWCNTs filled epoxy also represented improved mechanical strength and electrical resistivity. Keywords: MWCNT, Silica, Epoxy, PDMS.