In order to exert the synergistic photocatalytic effect of nano-noble metal and polymer matrix, hexagonal boron nitride nanosheets (h-BNNS) were doped with C and O elements by RGO to obtain porous doped boron nitride materials (BCNO), and silver nanoparticles (Ag NPs) were loaded on BCNO matrix by hydrothermal method to prepare BCNO/Ag composites. The composition, microstructure and photocatalytic properties of the composites were characterized. The photocatalytic properties of BCNO/Ag composites were tested by reducing CO2 to CO as a reaction model. The results show that boron nitride modified by nonmetal doping still has a stable polycrystalline structure; After loading Ag NPs, the plasma resonance effect of Ag NPs not only significantly enhances the absorption ability of BCNO matrix to ultraviolet-visible light, but also improves the separation efficiency of its photogenerated carriers; During the preparation of composite materials, the composite material obtained with the addition of 3.0% silver and the calcination temperature of the composite sample at 130 ℃ exhibits the best photocatalytic performance, and the conversion rate of CO2 to CO is 4.68 μmol/（g·h）. Therefore, h-BNNS modified by doping can better stably load nano-precious metals, thus giving full play to the synergistic photocatalytic performance of Ag nanoparticle and BCNO, which provides a theoretical basis for the effective composite and performance research of organic-inorganic nanophotocatalyst.