The invention relates to a multifunctional inorganic interior wall coating and a preparation method thereof. The coating comprises the following components in percentage by weight: 5-15 percent of potassium silicate, 2-5 percent of lithium silicate, 5-20 percent of silica sol, 5-15 percent of diatomite, 5-10 percent of shell powder, 5-15 percent of photosensitive auxiliary-supported tourmaline, 5-15 percent of radiation-resistant-bactericidal auxiliary-supported bentonite, 1-10 percent of nano SiO2 dispersing liquid, 2-8 percent of calcined kaolin, 3-12 percent of anatase titanium dioxide, 2-8 percent of alumina powder and 10-25 percent of water; the total percentage by weight of all the components is 100 percent. The preparation method provided by the invention is simple; the obtained interior wall coating has the advantages of being non-toxic, odorless, green and environment-friendly, radiation-resistant, bactericidal and bacteriostatic, capable of eliminating formaldehyde and other organic pollutants, self-clean, capable of purifying air, releasing negative oxygen ions and regulating the humidity, fire-proof and flame-retardant, high temperature-resistant, water-resistant, scrubbing-resistant, aging-resistant, powdering-resistant and corrosion-resistant, thereby having wide market prospect.