The invention relates to a core-shell-structured nano-zinc oxide coated nano-copper oxide composite antibacterial agent as well as a preparation method and an application. The preparation method comprises the following steps: dissolving copper nitrate and sodium carbonate in water respectively, adding a surfactant in the copper nitrate solution, then dripping the sodium carbonate solution in the copper nitrate solution, reacting and then carrying out centrifugal separation, washing, drying and roasting to obtain black nano-copper oxide; adding the nano-copper oxide in water, stirring, adding zinc nitrate and dissolving the zinc nitrate, dripping ammonia water to adjust the pH value to be about 7 and then obtaining a solid powder, and carrying out centrifugal washing, drying and calcining on the solid powder to obtain nano-zinc oxide coated nano-copper oxide. The nano-zinc oxide coated nano-copper oxide composite antibacterial agent prepared by the method disclosed by the invention has a light colour, can be used for most of household appliances, furniture, wall surfaces and other light-colour areas, and has a high inhibition effect on common bacteria and fungi due to the antibacterial complementary effect of zinc oxide and copper oxide.