In order to prepare an epoxy resin (EP) with good thermal conductivity that can be used in micro-electronic components, three kinds of monomers containing terminal epoxy groups (Si-EP) with different structures were prepared, and the prepared Si-EP monomers were then used as organic phases to blend with E-51 epoxy (EP) to prepare new epoxy Si-EP/EP resin, respectively. The thermogravimetry (TG) was employed to research the thermal properties of cured Si-EP/EP resins, while the dielectric properties and thermal conductivities are also investigated. The results showed that the addition of three kinds of Si-EP monomers can greatly improve the thermal conductivities of Si-EP/EP resin, whose optimal value is 0.1973 W/mk, increased as much as 16.18% than that of pure EP (0.1700 W/mk). While the maximum initial decomposition temperature of Si-EP/EP is increased from 325 degrees C of pure EP to 344 degrees C, their initial thermal degradation temperature is 395 degrees C, which is also higher than that of the pure EP resin (381 degrees C). However, the addition of Si-EP/EP did not damage their dielectric constant and dielectric loss. The enhancement of thermal conductivity of Si-EP/EP resins can be owning to the high thermal resistant Si-contained resins, as while as benefits from the cross-linking network structure formed inside the resin. This study has great application potential in improving thermal conductivity of EP without decreasing their dielectric properties.