Abstract: To screen novel anti-dengue virus (DENV) NS5 RdRp enzyme inhibitors, a series of 5-cyano-2-thiacetoaryl pyrimidinone compounds were designed and synthesized by molecular hybridization method with HCV NS5B RdRp inhibitor 3jc and ZIKV NS5 RdRp inhibitor 4w as lead compounds. The anti-DENV activity of these compounds was evaluated by MTT assay and plaque assay and five compounds showed anti-DENV activity. The most active compound 7a'k showed better anti-DENV activity than that of the positive control ribavirin (EC₅₀ = 7.86 μmol·L^-1 vs EC₅₀ = 18.07 μmol·L^-1), and the other four compounds showed almost the same anti-DENV activity as ribavirin. Finally, the prediction and simulation of the binding mode through molecular provided new ideas for the further development of this new DENV NS5 RdRp inhibitor.