Abstract: Zn_xCd_1−xS solid solution photocatalysts with high photocatalytic activity were prepared by the coprecipitation method at room temperature. The optimum process conditions of Zn_xCd_1−xS photocatalyst for degradation of landfill leachate (LFL) under simulated light and the hydrogen production rate for decomposition of degraded LFL were investigated, including the effects of Zn atom content, the amount of photocatalyst and illumination time on COD removal efficiency and hydrogen production performance. Results show that Zn_xCd_1−xS exhibits the highest photocatalytic activity with Zn∶Cd = 1∶1. Moreover, when the concentration of Zn_0.5Cd_0.5S is 1.0 g/L, and reaction time is 3 h, the COD removal efficiency of LFL can be up to 30.85% at room temperature. At the same time, Zn_0.5Cd_0.5S was applied to decompose degraded LFL to produce hydrogen. When the input amount of Zn_0.5Cd_0.5S is 0.6 g/L and illumination time is 3 h, the maximum hydrogen production is 1533 µmol, and the H₂ production rate is 8312 µmol/(g·h). The hydrogen production obtained in this process is much higher than that of photocatalytic decomposition of pure water. After three recycles, the hydrogen production can still remain above 83% of the initial hydrogen production.