With the acceleration of urbanization and the increase of pollutant discharges in China, the pollution load of water body in many cities have exceeded the natural self-purification capacity of water bodies, resulting in the deterioration of water quality, or even the occurrence of black and odorous water bodies. The urban black and odorous water bodies, as current water environment issue in China, have aroused a strong public concern. In this paper, the origin and pollution source of black odor in water are analyzed from the aspects of point source, non-point source, endogenous and hydrodynamic conditions. Subsequently, the TiO₂/g-C₃N₅ composite photocatalytic material was prepared by hydrothermal method and high temperature calcination method. The results showed that the degradation rate of methylene blue (MB) reached 91.5% and the degradation rate of tetracycline hydrochloride (TCH) reached 92.4% in 105 min. The high degradation rate can be attributed to the effective combination of the introduced TiO₂ and g-C₃N₅ to form a heterojunction, with the excellent visible light response characteristics of g-C₃N₅, the photocatalytic performance is significantly improved.