Via a vacuum thermal treatment, oxygen vacancy (O-v) was introduced into TiO2 bulk lattice during the phase transformation from amorphous TiO2 to anatase. High-resolution transmission electron microscopy (HRTEM), Raman spectra and X-ray diffraction (XRD) confirm the involvement of O-v causes more violent changes in both bulk and surface structure. Electron paramagnetic resonance (EPR) demonstrated as-obtained V350 gets about a 40-times enhanced O-v signal compared with pure TiO2 (A350) and a 10-times larger signal than that of common O-v modified TiO2 (A450-V350), which clearly illustrates the high concentration of O-v in its bulk lattice. The much enriched O(v)s in both bulk and surface lattices of TiO2 help V350 get an enhanced capacity in either visible light harvest or photocarriers generation. And a much higher visible photocatalytic activity for Aicd Orange 7 degradation was finally achieved by V350. (C) 2018 Elsevier B.V. All rights reserved.