BiVO4/TiO2−x heterojunction is built via a two-step hydrothermal process. Self-doped of Ti3+ creats a donor energy level under the conduction band of TiO2. Ti3+ donor energy level satisfies the band-matching of BiVO4/TiO2−x heterojunction. BiVO4/TiO2−x heterojunction exhibits high photocatalytic activity.