Abstract: In order to obtain an efficient and low-consumption harmful algae pollution prevention method, a novel visible-light responsive photocatalyst b-N-TiO₂/Ag₃PO₄ was successfully synthesized via a calcination-precipitation technique. The synthesized photocatalyst was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (DRS). The obtained results highlighted that: (1) b-N-TiO₂ was uniformly dispersed on the surface of Ag₃PO₄, which significantly broadened the light response range of Ag₃PO₄ and effectively facilitated the separation of electron-hole pairs in the composite b-N-TiO₂/Ag₃PO₄. (2) The b-N-TiO₂/Ag₃PO₄ (0.2T/A) photocatalyst exhibited the highest photocatalytic activity for the degradation of Chla in Microcystis aeruginosa cells. The pseudo-first-order rate constant of b-N-TiO₂/Ag₃PO₄ (0.2T/A) was 2.73 and 7.72 times that of pure Ag₃PO₄ and b-N-TiO₂, respectively. After 8 h visible light irradiation, the composite b-N-TiO₂/Ag₃PO₄ (0.2T/A) was able to remove approximate 98.1% Chla in algal cells. Even after 3 cycles of recycling, the elimination rate of Chla remained at 85.4%. (3) The immobilized b-N-TiO₂/Ag₃PO₄ exhibited excellent photocatalytic activity for degrading algal cells and microcystins in surface water. Therefore, the b-N-TiO₂/Ag₃PO₄ composite material has potential application prospects in the treatment of harmful algae polluted water.