Samarium-doped ZnO Nanoparticles were synthesized via a facile and surfactant-free solvothernal method after calcined 3 h at 400 ℃. The prepared nanostructures were characterized by UV-vis spectrophotometer, scanning electron microscopy (SEM), energy dispersive spectrum analysis (EDX) and Fourier transform infrared spectroscopy(FTIR).The SEM images show that the synthesized ZnO nanoparticles are regular hexagonal columnar body. And the morphology of the nanostructures is not changed after doped Sm，while the crystal volume of ZnO-Sm nanoparticles become smaller. The EDX spectrum depict that Sm ions are successfully doped into ZnO. The photocatalytic studies show that the ZnO-Sm(2.0%) photocatalytic degradation of RhB enhanced approximately 30% under visible light irradiation compared with the pure ZnO. And in order to obtain the best photocatalytic effect, the optimal experimental conditions were explored. As such, ZnO-Sm nanostructures were indicated great potential for practical applications in wastewater treatment.