Bi₂MoO₆ is modified by rare earth ions (RE³⁺=Tb³⁺, Sm³⁺) for solving the problem of poor electron-hole pair separation efficiency of Bi₂MoO₆ in the photocatalytic reaction process. A series of Tb³⁺ and Sm³⁺ doped Bi₂MoO₆ photocatalysts were synthesized by the solvothermal method and named RE³⁺/Bi₂MoO₆ (RE³⁺=Tb³⁺, Sm³⁺). The composition, structure and morphology of the RE³⁺/Bi₂MoO₆ material were characterized by various analytical means. The photocatalytic activity of the samples was investigated by using the organic dye rhodamine B (RhB) as a simulated pollutant under visible light. The results show that the doping of rare earth Tb³⁺ and Sm³⁺ ions increases the specific surface area of the sample, optimizes the energy band structure, expands the visible light absorption range, and improves the separation efficiency of photogenerated electron-hole pairs. The photodegradation rates of 4% Tb³⁺/Bi₂MoO₆ and 4% Sm³⁺/Bi₂MoO₆ samples in 50 mL 10 mg/L RhB reached more than 95% under visible light, which are nearly two times higher than that of the pure Bi₂MoO₆.