Graphene oxide (GO) film was modified by silane coupling agent KH-560, then bismuth vanadate (BiVO₄) was successfully loaded on the modified GO film via hydrothermal method to obtain reduced graphene oxide (RGO) film based BiVO₄ composite. The effects of hydrothermal reaction time on BiVO₄ morphology and photocatalytic properties were investigated by scanning electron microscopy (SEM), X-ray diffraction pattern (XRD), ultraviolet visible light absorption spectroscopy (UV-vis) and photocatalytic activity. The results show that BiVO₄ is a porous structure growing towards (040) crystal plane on the composite, and when the synthesis time is 6 h, the degradation rate for Reactive Black 5 by the composite can reach 95 % within 90 min. Furthermore, the composite prepared at the optimal time was characterized by transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The microphysical process of the separation and combination of photogenerated electron hole pairs was successfully demonstrated by the variations of photoinduced current density with time (i-t curve) and electrochemical impedance spectroscopies (EIS). Finally, the photocatalytic mechanism was proposed by free radical capture experiment.