Abstract: In order to improving the antibacterial activity property of inorganic copper-based fungicides, Cu2O nanocrystal was prepared via a facile one-pot synthesis by the reduction of fructose in the paper. The sample was characterized by XRD and SEM. In addition, their antibacterial activity of Cu2O nanocrystal and its mixtures containing ZnO and methenamine were also investigated by inhibition zone method. The result suggested cuprous oxide presented active inhibition to Colletotrichum glecosporioides, Valsa mali, Cucumber wilt and Gaeumannomyces graminis var tritici. The inhibition rate of cuprous oxide was more than 90% once its concentration was 0.5 mg/mL. At the same time, the better antibacterial activity to Colletotrichum capsici and Coniothyrium diplodiella, was reached when the mass of ratio of ZnO or methenamine and Cu2O was up to 1:2 respectively. The synergism was disclosed in our experiments.