Polyaniline/nano-TiO 2 composite was prepared by polyaniline for the surface modification of nano-TiO 2 particles, and was characterized via Fourier-transform infrared spectra, UV-Vis-NIR spectrophotometer, wide-angle X-ray diffraction, thermogravimetric analysis and transmission electron microscope, as well as conductivity. Surface area, total pore volume and pore size distribution of nano-TiO 2 particles and polyaniline/nano-TiO 2 composite particles were also measured. The results of spectroanalysis illustrate that polyaniline and nano-TiO 2 particles are not simply blended or mixed up. There is a strong interaction between polyaniline macromolecule and nano-TiO 2 particles. Synthesized polyaniline was deposited on the surface of nano-TiO 2 particles, forming a core-shell structure. The dimension of polyaniline/nano-TiO 2 composite particles is in the range 25-40nm. Polyaniline/nano-TiO 2 composite contains 38% conducting polyaniline by mass, for which conductivity reaches 0.75Scm - 1 at 25 o C.