Titanium dioxide (TiO2) based materials were used in many fields such as energy application, biological and environment remediation control. In this study, copper-doped TiO2 (Cu-TiO2) was synthesized and investigated for photocatalytic water splitting hydrogen (H-2) evolution. The doping of Cu ions not only increased the oxygen vacancies but also improved the charge separation of photocatalyst. The Cu-TiO2 displayed a higher the rate of H-2 evolution (45.6 mmol/h) as compared to undoped TiO2 (0.73 mmol/h). The reused of material was identified and the photocatalytic water splitting mechanism of Cu-TiO2 was proposed. The results showed that, Cu-TiO2 had high stability after reusing for 5 consecutive cycles without the loss of H-2 production capacity. In addition, practical application and future research were discussed in details. This work may contribute to the potential application of TiO2-based photocatalyst for water splitting in order to produce H-2 gas as green energy.