The invention provides composite antibacterial powder and a preparation method thereof. The composite antibacterial powder contains nano silver, zinc and nonmetallic minerals such as nano calcium carbonate or nano hydrotalcite, nano titanium oxide and nano bentonite and the like serving as carriers, wherein the content of the silver is 10 to 20 mass percent, and the content of the zinc is 20 to 40 mass percent. The composite antibacterial powder has high bactericidal factor content, is more convenient in compatibility and application, and saves the cost; the particle diameter of the bactericidal factors is nano-scale, so that the bactericidal capability is stronger; the composite antibacterial powder has illumination resistance, does not change color, and has high temperature resistance, good slow-release property and long-acting property; and the preparation method is simple in process, time-saving, labor-saving and high in production efficiency. The composite antibacterial powder serving as an antibacterial agent can be widely applied to various building materials, glass, coating (containing powdery coating), wood, paper and products thereof, plastics, plastic cement, daily ceramic, chemical materials, various home appliances, daily chemical products, textiles and the like.