To design efficient photocatalysis system, the recombination of electron-hole pairs in photocatalysts should be suppressed. Herein, p type Cu2-xSe/n type CdS composite photocatalyst was proposed for the first time to improve photocatalysis performance for Rhodamine B (RhB) degradation. Among the various ratio composites, 10 wt% Cu2-xSe/CdS shows the best photocatalysis performance, the degradation rate of RhB was enhanced 7.8 times than that of pristine CdS. The enhanced photocatalysis performance was mainly ascribed to the formation of Cu2-xSe/CdS p-n junction, which will lead to effective charge separation in the composite photocatalyst.