TiO2-OV photocatalyst with suitable content of oxygen vacancy (OV) were prepared by a simple solid-state chemical reduction method using nano TiO2 (P25) as raw material. XRD, SEM, XPS, EPR and UV-Vis DRS spectra were used to test the structure, morphology, elemental composition, OV content and energy band structure of TiO2-OV, respectively. Combined with photocatalysis experiment and photoelectric chemical measurement, the photocatalytic H2O2 production by TiO2-OV prepared with different amounts of NaBH4 (when the amount of P25 is 2.0g, the same below) was investigated. And the photocatalytic reaction mechanism was speculated based on the capture experiment of active species. The results show that TiO2-OV is a highly crystalline mixture of anatase and rutile phase. When the amount of NaBH4 was 10 mg, the direct band gap energy (Eg) of the prepared material TiO2-OV-10 is 2.77 eV, and the conduction band (CB) is -0.84 eV, showing the best photocatalytic H2O2 performance. The production efficiency of H2O2 was 1752.8 μmol/(g·h) under simulated sunlight irradiation. The reason why the photocatalytic H2O2 production efficiency can be shown after NaBH4 heat treatment reduction is that OV is generated on the surface of TiO2, and oxygen vacancy with appropriate concentration can be used as an electron trap, thus improving the separation efficiency of photogenerated electron-hole. After 4 times of recycling, the catalytic performance decreased slightly. The active species of H2O2 photocatalyzed by TiO2-OV are superoxide radical (?O2-), hydroxyl radical (?OH) and hole (h+). In addition, CH3OH plays an important role in promoting photocarrier separation and generating H2O2. This paper provides a reference for the design strategy of semiconductor photocatalyst and a new perspective for understanding the mechanism of photocatalytic production of H2O2.