Preparation method of natural kelp iodine additive

The invention relates to a preparation method of a natural kelp iodine additive. The preparation method comprises the following steps: drying and crushing kelp; adding kelp powder into 4-6-fold ethanol-water solution in terms of mass, and performing microwave extraction twice to obtain a kelp extract; concentrating the extract to 63-75% of the mass of the raw material, and separating out a lower water layer; allowing the water layer to stand still for 1-4h at room temperature, and performing vacuum suction filtration to obtain mannitol powder and filtrate; adding 1.20-2.70-fold water in terms of mass into the filtrate, adding 0.30-0.70-fold wall material and 0.03-0.08-fold emulsifier in terms of mass into a water bath while stirring to obtain a mixed solution; performing spray drying on the mixed solution to obtain powder, adding the mannitol powder and/or maltodextrin, and uniformly mixing to obtain the natural kelp iodine additive. The natural kelp iodine additive prepared according to the preparation metho