Abstract: On the basis of solid phase sintering to prepare single-phase Sr₂Bi₂O₅, a series of CdS/Sr₂Bi₂O₅ composite photocatalytic materials were prepared by chemical precipitation method to solve the problem of organic pollutants in environmental pollution. The composite photocatalyst was characterized by XRD, SEM, TEM, EDS and XPS, and its photocatalytic performance was evaluated by degrading MB. After experiments, it is found that the CdS/Sr₂Bi₂O₅ composite photocatalyst consists of two phases: CdS and Sr₂Bi₂O₅. The morphology of agglomerated Sr₂Bi₂O₅ particles is attached to the irregular CdS particles, and the surface of the two phases are in close contact with each other, forming an obvious boundary, and forming a heterojunction. When CdS/Sr₂Bi₂O₅ mole ratio is 1/1, the visible photocatalytic performance is the best, the degradation efficiency of MB reached 95% in 40min, and three cycle tests show that the photocatalyst had good stability and repeatability. The significantly improved photocatalytic performance is mainly attributed to the formation of heterojunction between CdS and Sr₂Bi₂O₅ phases in the composite photocatalyst, which accelerates the separation of photoelectron-generated hole pairs and effectively inhibits the recombination of photoelectron-generated hole pairs.