The mixed-phase heterostructured TiO2 nanotree arrays were synthesized by a secondary hydrothermal route, and Ti3+ ions were introduced into the arrays for enhanced photoelectrochemical performance. The results show that the arrays consist of heterostructures with anatase and ruffle phases. XPS results indicate that during the hydrogenation process, part of Ti4+ ions transform to Ti3+ ions. Although the band gap shifts by only 0.1 eV, introduced defects and Ti3+ ions can greatly increase the efficiency of electron-hole separation. Photocurrent of the heterostructured TiO2 nanotree arrays with introduced Ti3+ ions increases by 41 times, and the photocurrent density enhances from 0.0055 to 0.2272 mA/cm(2).