Abstract: In order to achieve effective degradation of residual xanthate in flotation wastewater, TiO₂/diatomite binary composite photocatalyst was firstly prepared by oil bath precipitation method, and the effects of TiO₂ loading amount and H₂O₂ addition amount on the xanthate degradation performance of the product were investigated under the UV irradiation. Based on the optimized binary composite photocatalyst, BiOCl/TiO₂/diatomite ternary photocatalyst was then prepared by water bath precipitation method, and the effect of BiOCl loading amount on the xanthate degradation performance of the ternary photocatalyst was explored. The results showed that the binary composite photocatalyst possessed the optimal degradation performance to xanthate when the mass ratio of TiO₂ to diatomite was 1 GA6FA 5 and the amount of H₂O₂ with the concentration of 30% was 2 mL. The degradation efficiency of xanthate was about 60% within 60 min under the condition. Furthermore, the ternary photocatalyst showed the optimal photodegradation performance to xanthate when the mass ratio of BiOCl to TiO₂ and diatomite was 1 GA6FA 2 GA6FA 10. The degradation efficiency of xanthate could reach more than 90% within 90 min under the circumstance. Compared with the binary composite photocatalysts, BiOCl/TiO₂/diatomite ternary photocatalysts can not only achieve the degradation of xanthate from higher energy UV light to common visible light, but also show better degradation performance of xanthate, showing the potential practical application prospect.