Abstract: Pesticide pollution of water body is a potential threat to human health. In this study, a new S_0.1-(0.3/0.7)BiOI/BiOBr (S_0.1BBI_0.3) photocatalyst was synthesized by one-step solvothermal method. The structure, morphology and optical properties were characterized by XRD, SEM, XPS, UV-Vis DRS, EIS and other methods. S_0.1BBI_0.3 is a flower-like microsphere structure formed by the accumulation of two-dimensional nanosheets. Z-type heterojunction and S-doped dual-strategy co-modification broaden the photoresponse range of BiOBr, effectively prevent the photogenerated electron-hole pair recombination in S_0.1BBI_0.3, improve the photogenerated carrier redox ability, and increase the specific surface area. It provides more mesoporous structures, significantly improves adsorption properties, and provides more active sites for photocatalytic reactions. The photocatalytic experiment results showed that S_0.1BBI_0.3 had the best adsorption and photocatalytic performance for 2, 4-dichlorophenoxyacetic acid (2, 4-D) under visible light, and the removal rate of 2, 4-D was up to 91.8% under 45 min darkness and 120 min light conditions. Electron spin resonance (ESR) technology confirmed that \text•\rmO_2^ - is a photocatalytic active substance of S_0.1BBI_0.3.