To explore the effect of phase composition on the photoelectric property of anatase-rutile mixed crystal nanoparticles, a series of TiO2 nanoparticles with phase junctions controlling were synthetized by hydrolysis of TiCl4 in hydrochloric acid, an ionic liquid-assisted method was used during this process. Crystalline size and the ratio of anatase to rutile of as-prepared samples were calculated by the XRD. The surface area was measured by nitrogen sorption measurements using the BET method. The micro-structure of phase junctions was characterized by TEM. Optical transmittance properties of TiO2 with controllable phase junctions were examined via ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS). The particles were manufactured into films using the doctor-blade technique on FTO glasses. To test photocurrent density, and spatial separation capacity of electron-holes pairs, photo-electro method was employed. The photocatalytic activities of the resulting samples were examined in the degradation of methyl orange (MO) under artificial solar light irradiation. Mechanisms of separation and transfer of photogenerated charge and the effect of phase composition on photoelectric property of anatase-rutile nanoparticles were discussed. (C) 2014 Elsevier B.V. All rights reserved.