The invention discloses a preparation method of a negative ion coating with a virus and bacterium removing function. The preparation method comprises the following steps: weighing required raw materials according to a formula of the negative ion coating; crushing, grinding and ball-milling the weighed calcium carbonate powder, volcanic rock powder, negative ion powder, diatomite powder, sulfur powder, quartz powder, glutinous rice flour, titanium dioxide and bamboo charcoal powder; putting the superfine powder A into a closed stirring kettle for stirring operation; putting the mixture B, deionized water, an antibacterial agent, an anti-corrosion and anti-mildew agent, a dispersing agent, a compatilizer, an anti-freezing agent, a leveling agent and a cosolvent into a closed mixing machine for mixing operation; adding the weighed glycerol, plant essential oil, defoaming agent and thickening agent, and continuously mixing. Compared with the prior art, the negative ion coating has excellent antibacterial and bactericidal properties, is beneficial to removing viruses and bacteria, has the advantages of no toxicity, no harm, strong adhesion and uniform mixing of raw materials, has excellent use effect, simple preparation process and high production efficiency, and lowers the production cost.