To improve the dielectric properties and thermal conductivities of epoxy resins (EP), titanium dioxide super ne powders with microspheres structure (S-TiO 2 ) were prepared via a hydrothermal process based on the sodium dodecyl benzene sulfonate and hydroxyl silicate. The different content of S-TiO 2 was then employed as modi ers to add into EP resin to prepare the S-TiO 2 /EP composites. The structure and morphology of the prepared S-TiO 2 was observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and in uences of different addition of S-TiO 2 on the thermal conductivity of S-TiO 2 /EP composites are researched, while their dielectric constant and dielectric loss are also studied.The results suggested that the reasonable content of S-TiO 2 can endow the S-TiO 2 /EP composites with higher dielectric constant without excessive increase their dielectric loss even under the high frequency.Furthermore, the thermal conductivity of S-TiO 2 /EP are also be improved, which can be attributed to the good thermal conductivity of S-TiO 2 itself and the thermal conductivity path formed by S-TiO 2 inside the EP matrix.