Abstract: In order to achieve the reduction and removal of butyl xanthate, the residual flotation agent in mineral processing wastewater, TiO₂ and 3-amino 1,2,4-triazole were used as raw materials to prepare nitrogen-rich graphite phase carbon nitride (g-C₃N₅) supported TiO₂ composite photocatalyst (TiO₂/g-C₃N₅) by ultrasonic dispersion combined with direct thermal polymerization. The crystal form, morphology and optical properties of TiO₂/g-C₃N₅ composite photocatalyst were characterized by XRD, TEM, UV-vis DRS and PL, and it was applied to the photocatalytic degradation of butyl xanthate (SBX) solution. The effects of catalyst dosage, initial concentration of SBX solution and pH value on the photocatalytic degradation performance were investigated, and the cyclic stability of TiO₂/g-C₃N₅ composite photocatalyst was investigated. The results show that TiO₂ particles are uniformly dispersed on g-C₃N₅ nanosheets, which increases the number of active sites. The formation of heterojunction improves its response to visible light, extends its spectral range, promotes the separation of photoelectron-hole and improves its photocatalytic activity. At the conditions of pH=7, catalyst dosage 50 mg, SBX solution initial concentration 55 mg/L, illumination 5 h, the photocatalytic degradation rate of SBX solution by TiO₂/g-C₃N₅ composite photocatalyst reached 99.98%, and it had good stability.