The invention relates to a method for preparing a food-grade amino acid ferrous chelate compound without interfering anions, which selects amino acid and an iron source as main raw materials and is characterized by comprising the following steps: selecting glycine, methionine, glutamic acid, lysine and the like as amino acid raw materials, and selecting pure iron elements, ferrous oxide, ferrous hydroxide, ferrous carbonate and the like as the iron source, wherein the reaction mol ratio of the amino acid to the iron source is 1:1-6:1; and dissolving the amino acid in water, adding the iron source, adding a non-interfering anionic reducing agent or a complex reducing agent such as citric acid, ascorbic acid, acetic acid, carbonic acid and the like, adjusting the pH value to between 3 and 8, heating the mixture to between 40 and 100 DEG C, stirring the mixture to react for 5 to 70 hours, performing evaporation concentration, and extracting the mixture with 50 to 100 percent aqueous solution of ethanol, or performing spray drying or roller drying directly to obtain the required product. The product can be added with auxiliary agents of maltodextrin, cyclodextrin and the like, thus the method has the characteristics that the product has no interfering anions, the ferrous content is high, the preparation process is simple, and the like.