Preparation method of ferrous glycine sulfate complex

The invention provides a preparation method of a ferrous glycine sulfate complex. The preparation method comprises the following steps: dissolving glycine and ferrous sulfate into water, adding a small amount of iron powder and multiple drops of concentrated sulfuric acid, carrying out rotation reaction at 70-90 DEG C, cooling to 50-65 DEG C to crystallize, then carrying out suction filtration to obtain crystalline solids, washing the crystalline solids for several times with absolute ethyl alcohol, and carrying out natural airing, so as to obtain the ferrous glycine sulfate complex. The crystallization temperature in the preparation method is 50-65 DEG C and is 25 DEG C higher than that of an existing method, so that the time of the cooling crystallization process is shortened, and the energy consumption in the refrigeration cooling process is reduced; and meanwhile, the yield of the ferrous glycine sulfate complex prepared by virtue of the method is high, the product contains a small amount of crystal water, and the energy consumption in the subsequent drying process of the product is low.