The invention relates to an acid soil regulator with a plant nutrient function and a preparation method thereof. The acid soil regulator is prepared by uniformly mixing basic materials and auxiliary materials, wherein the basic materials are prepared by mixing and fermenting brewer's grains, peat soil, traditional Chinese medicine dregs, soybean meal powder, straw powder, edible fungi dregs, pineapple paste, apple paste, silkworm excrement, proteolytic enzyme, nitrogen-immobilizing bacteria, rhizobium, potassium-decomposing bacteria, cellulose decomposing bacteria, antibiotic producing bacteria and water; the auxiliary materials are prepared by uniformly mixing earthworm manure, charcoal residues, urea, plant ash, lime powder, urea iron complex, and chelated zinc. The preparation method comprises the following steps of A, preparation of the basic materials; B, preparation of the auxiliary materials; C, preparation of the soil regulator. The acid soil regulator has the advantages that multiple rich and absorbable nutrients are provided for the plant growth, the problem of soil caking is effectively solved, the air ventilating property of the soil is improved, the acidity of the soilis reduced, and the fertilizer-maintaining and water-maintaining ability of the soil is enhanced. The preparation method has the advantages that the preparation method is simple, the implementing iseasy, the investment cost is low, and the preparation method is suitable for large-area popularizing.