The invention relates to a paint technology, an environment-friendly technology and an antibacterial mould-proof technology, in particular to high-efficiency environment-friendly antibacterial mould-proof inorganic composite nano paint and a preparation method thereof. The high-efficiency environment-friendly antibacterial mould-proof inorganic composite nano paint comprises the following components in percentage by weight: 0.5 to 5 percent of wetting dispersant, 0.01 to 20 percent of inorganic composite nano antibacterial agent concentrated pulp, 0.5 to 10 percent of hydrophobing agent, 0.5 to 10 percent of anionic powder, 0.5 to 8 percent of film-forming aid, 0.1 to 2 percent of anti-settling agent, 0.8 to 10 percent of antifreezing agent, 0.1 to 3 percent of defoaming agent, 4 to 30 percent of pigment, 0 to 30 percent of filler, 15 to 45 percent of emulsion, 0.1 to 4 percent of thickening agent, 0.1 to 3 percent of flatting agent, 0 to 3 percent of pH regulator and 0.5 to 45 percent of water. The high-efficiency environment-friendly antibacterial mould-proof inorganic composite nano paint is mainly prepared by adding the inorganic composite nano antibacterial agent into the basic materials, so that the paint has the coating characteristic of high performance, is low is cost, and has a function of purifying air, can eliminate harmful gas volatile organic compounds (VOC), formaldehyde and the like and also has a durable and high-efficiency antibacterial mould-proof function, so that the sterilizing rate within 6 hours reaches 100 percent and the mould-proof grade reaches the first grade. By the high-efficiency environment-friendly antibacterial mould-proof inorganic composite nano paint and the preparation method thereof, self-cleaning performance, hydrophobicity, scrubbing resistance, dirt resistance and weather resistance of the coating are improved; and the high-efficiency and durable antibacterial and mould-proof effect is achieved.