The invention discloses multifunctional environmentally-friendly water-based paint. The multifunctional environmentally-friendly water-based paint comprises main materials, additives and deionized water, wherein the main materials include diatom ooze, maya blue, tourmaline, nanometer titania, ultra-fine aluminum silicate, sepiolite, silicon carbide and zinc fluosilicate; the additives include acrylate polymer emulsion, silver ion solution, fluoro-silicone emulsion, wetting dispersant, preservative, polyvinyl alcohol, a thickener, hydroxypropyl methyl cellulose, a buffering agent, a defoaming agent, an anticracking agent and inorganic pigment. The invention also discloses a preparation method of the multifunctional environmentally-friendly water-based paint. According to the multifunctional environmentally-friendly water-based paint, the raw materials are environmentally-friendly, nontoxic and pollution-free materials; maya blue, nanometer titania and diatom ooze are used in match to enable efficient function of resisting formaldehyde, ammonia and benzene; the silver ion solution and nanometer titania are used in match to enable effective antibacterial effect and long-lasting antibacterial effect; tourmaline and silicon carbide are added, so that the functions of health care, smell removing and fireproofing are realized.