Abstract: The heterostructure LaCO₃OH/In(OH)₃/In₂S₃ photocatalysts were synthesized by in-suit wet chemical method. The composition, structure and morphology of the prepared heterostructure LaCO₃OH/In(OH)₃/In₂S₃ photocatalysts were investigated by characterization technologies such as XRD, SEM, XPS, BET and TG. The photocatalytic activity of the heterostructure LaCO₃OH/In(OH)₃/In₂S₃ photocatalysts was evaluated by degradation of dye Rhodamine B under visible light (λ ≥ 420 nm). The results show that when the molar ratio of La/In is 15mol%, the obtained heterostructure LaCO₃OH/In(OH)₃/In₂S₃ photocatalyst holds the best photocatalytic activity. And the activity is twice as that of the In(OH)₃/In₂S₃ photocatalyst. It is because that the obtained heterostructure LaCO₃OH/In(OH)₃/In₂S₃ photocatalyst has higher BET surface, proper energy band structure and optimal absorption capacity. Using terephthalic acid (TA) as probe molecule, the photocatalytic experiment demonstrates that hydroxyl radical is the key active species. The possible degradation mechanism was proposed.