The invention relates to a multifunctional inorganic diatom ooze coating, which is prepared from the following components in percentage by mass: 10%-25% of water, 0.4%-0.8% of cellulose, 10-30% of a mixture of potassium metasilicate and silica sol, 0.2%-0.4% of a stabilizer, 0.1%-0.3% of a dispersing agent, 0.1%-0.3% of a silicon additive, 0.3%-0.5% of a defoaming agent, 0.1%-0.3% of an antibacterial agent, 0-20% of titanium dioxide, 5%-15% of nanometer kieselguhr, 10%-30% of coarse whiting, 2%-4% of talcum powder, 1%-3% of medical stone, 0-1.5% of anion, 0-2% of a nano-photocatalyst, 1%-2% of inorganic gel powder, 0-9% of an order-removing emulsion and 0-1.5% of pigment, wherein the sum of the components is 100%. The invention also provides a preparation method of the coating. The coating disclosed by the invention has the functions of sterilizing, preventing mold, purifying air and the like; and the preparation method disclosed by the invention is simple and easy to operate.