With porous SiO₂ as the carrier, Cu₂O/CPAN/SiO₂ (cuprous oxide/cyclized polyacrylonitrile/silicon dioxide) composite photocatalyst was prepared by solution impregnation and in situ thermal decomposition. The morphology, composition and structure of the composite were characterized by TEM, SEM, XRD, FTIR, BET and EDS, and the photoelectric properties of the composite particles were analyzed by UV-VIS, DRS, PL, EIS and photocurrent methods. The photocatalytic catalytic properties of Cu₂O/CPAN/SiO₂ composite particles were estimated through the photoreduction of p-nitrophenol with visible light. The results showed that porous SiO₂ carrier greatly increased the specific surface area of Cu₂O/CPAN. The heterojunctions of Cu₂O in octahedral crystal and CPAN are evenly distributed on the surface of SiO₂ and significantly improve the absorption of visible light and the separation efficiency of photogenerated electron-hole pairs. When the Cu₂O content is 2%, the heat treatment temperature is 260℃, and the heat treatment time is 3h, the prepared Cu₂O/CPAN/SiO₂ composite particles exhibit the best photocatalytic activity. The method can effectively improve the specific surface area and electron-hole separation efficiency of the material, and provides a method basis for preparing a high-efficiency composite catalyst.