TiO2-MWCNT core/shell heterostructures containing a single MWCNT have been successfully prepared via solvothermal method. TiO2-MWCNT heterostructures with different morphologies and electromagnetic (EM) properties have obtained by adjusting the weight ratio of titanium dioxide (TiO2) and multi-walled carbon nanotubes (MWCNT) (weight ratio: 1:1, 5:1 and 10:1). EDS spectrum and X-ray diffraction analysis reveal that the product is composed of Ti, O, and C elements, and the crystal structure of TiO2 is tetragonal anatase phase. SEM and TEM images show that the MWCNTs are coated by a thin layer of TiO2 crystals, and the average diameters of the needle-like TiO2 nanocrystals are less than 100nm. EM properties of the as-prepared TiO2-MWCNT heterostructures are investigated in the 0.5-18.0GHz range. The permittivity and permeability of the TiO2-MWCNT heterostructures change obviously as the weight ratio of TiO2 and MWCNT increases. Moreover, the typical resonance-antiresonance phenomenon can be observed in the permittivity and permeability curves.