Preparation method and application of long-acting natural multifunctional additive

A preparation method for a long-acting natural multifunctional additive. A natural filler is coated with a modified polymer; the modified polymer is obtained by modifying any one or more than two of a biodegradable polymer, a water-soluble polymer, polyvinyl chloride, polyamide, polyphenylene sulfide, melamine resin, polyolefin, polyhydroxyalkanoate, a styrene block copolymer, chlorinated polyvinyl chloride, urea-formaldehyde resin, polyurethane, and chitosan; and the natural filler is shell powder or eggshell calcined at high temperature, any one or more than two of calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, and purified Hermetia illucens pupa shell powder, or a compound of nanoparticles and calcined shell powder or eggshell powder. By adoption of the preparation method disclosed by the present invention, the cost is low, and part of raw materials are recycled wastes; the antibacterial property of the natural filler is long-acting, and the natural filler is easy to store; and the preparation method can be applied to various processing techniques, or the addition or adjustment of health care products.