A series of rGO/AgBr heterojunction photocatalysts were fabricated through a facile solvothermal method. The rGO/AgBr heterostructures were characterized by XPS, XRD, UV-Vis DRS, SEM, TEM, PL and the transient photocurrent responses. The XRD, SEM, XPS and TEM analyzes indicated that the graphene and silver bromide were successfully compounded without other impurities. The UV-Vis DRS exhibited that the composites have better optical properties than pure silver bromide. The PL and the transient photocurrent responses demonstrated that the addition of graphene significantly promotes the separation of photogenerated electrons and holes. Subsequently, the photocatalytic activities of rGO/AgBr composites were studied by degrading Rhodamine B (RhB). It turned out that the degradation rate of RhB by the rGO/AgBr heterojunction photocatalysts were significantly higher than that by pure AgBr. What’s more, to study the photocatalytic degradation mechanism of RhB by rGO/AgBr heterostructures, the trapping experiments were used to identify the main active components. This work confirmed that the photocatalytic degradation performance of the catalyst was greatly improved after doping graphene, which provided certain data support for degradation of organic contaminants in water.