In this work, a serious of Pr3+ doped Bi2WO6 had been prepared by one-step hydrothermal method without using any additive. XRD results showed that the Pr3+ doped Bi2WO6 possessed pure orthorhombic phase. XRD patterns shifted to higher angles with the doping amount of Pr3+ increasing indicated that Pr3+ was doped into the lattice of Bi2WO6. UV-vis DRS results revealed that the band gap was narrowed by Pr3+ doping. SEM and TEM images showed that the Pr3+ doped Bi2WO6 presented 3D flower-like microspheres constructed by many nanosheets. The photocatalytic activities of the as-prepared samples were evaluated by using rhodamine B (RhB) as the target organic pollutant. It was found that 1% Pr-Bi2WO6 exhibited excellent photocatalytic performance, as well as good stability and reusability. The improved photocatalytic activity can be ascribed to the optimum optical absorption activity, the larger specific surface area and the morphology of microspheres which resulted in the effective separation of the photogenerated electron hole pairs. In addition, the photocatalytic mechanism had been discussed according to the radical-trapping experiments.