Ag2S/g-C3N4/ZnO nanoarrays heterojunction with different amounts of Ag2S was synthesized by simple chemical method, and a core-shell structure was formed. ZnO acts as the core while g-C3N4 and Ag2S are the shells in order to absorb visible light and to restrain photo-corrosion. The optimal experimental condition and modifying amount have been investigated. The photocatalytic performance of g-C3N4/ZnO is 2 times than that of pure ZnO NRs. Layered-structure g-C3N4 offers the opportunities for rapid electron transfer process to enhance photocatalytic performance. The photocatalytic performance of the optimal material, as 15Ag(2)S/g-C3N4/ZnO, is 6 times than that of pure ZnO NRs. The broader range and stronger indensity absorption of visible light make great contribution to enhancing photocatalytic performance. Besides, the inter-built electrical field of g-C3N4 with ZnO and Ag2S ensure the efficient separation of photo-induced carriers. Therefore, the core-shell structure heterojunction of Ag2S/g-C3N4/ZnO can largely promote photocatalytic performance.