A combined procedure of sol-gel and microwave-assisted emulsion polymerization has been developed to prepare TiO2/polystyrene core-shell nanospheres with nano-scale TiO2 core and smooth and well-defined polystyrene shell. The core-shell structure and morphology were examined by TEM. The diameter and its distribution of the nanospheres were measured by dynamic light scattering. The nanospheres were characterized with Fourier transform infrared spectroscopy (FTIR). It is found that the diameter and its distribution of the TiO2/polystyrene core-shell nanospheres can be regulated by the concentration of styrene monomer in the emulsion solution.