In order to improve the photo-degradation performance of cuprous oxide and solve the problem of recycling, in the paper, ceramsite-Cu2O was prepared, and the composite degradation performance and mechanism was studied. The results showed that under the condition of no light and light, the degradation of three kinds of materials (ceramsite, Cu2O, ceramsite-Cu2O) were obvious different efficiency, and under the condition of light, the degradation efficiency improved obviously. This indicated that under the condition of light, the degradation performance and mechanism of ceramsite-Cu2O composite materials are both adsorbed degradation and photo-degradation. Analysis the degradation performance of ceramsite-Cu2O composite with H2O2, the resluts indicated that electronic - hole produced by Cu2O could accelerate the hydrolysis of H2O2, then, a lot of strong oxidizing groups could be produced, which could effectively improve the photo-degradation performance. Further analysis degradation mechanism of ceramsite-Cu2O , the process of degradation of pollutants could be divided into three phases: In the first phase, adsorption plays a leading role, which conforms to one dimensional linear model. In the second stage, photo-degradation plays an important role, which comply with y = -0.0069 x2 + 1.1843x + 26.978 model. The third stage leveled off.