Poor charge transfer and separation rate are the major bottlenecks for the activity and stability of BiVO4 photoanode. Here, we introduced oxygen vacancies into MoO3/BiVO4 heterojunction film by post-annealing the film in argon-saturated environment for improving its photoelectrochemical (PEC) water oxidation activity and stability. In comparison with the normal MoO3/BiVO4 film, the MoO3/BiVO4 film with oxygen vacancies is of better PEC water oxidation performance. Specifically, a higher photocurrent density of 4.1mA/cm(2) in 0.1M Na2SO4 at 1.1V versus SCE was achieved on the MoO3/BiVO4 film with oxygen vacancies, which is about 200% improved over the normal MoO3/BiVO4 film (1.83mAcm(-2), at 1.1V versus SCE). In addition, the MoO3/BiVO4 film with oxygen vacancies shows more stable activity and faster kinetics for water oxidation, without significant activity loss for 5h reaction at 1.23V versus RHE. The enhanced performance on such a MoO3/BiVO4 film photoanode can be attributed to that the oxygen vacancies accelerate the charge transfer and separation rate between film/electrolyte interface, and thus improve the water oxidation activity and restrain the anodic photocorrosion simultaneously.