The invention discloses an ionic rare earth tailing soil improver and a preparation method thereof. The soil improver aims to solve the technical problem that the soil texture and the physical and chemical structures of the soil are destroyed as ecology of the conventional ionic rare earth tailing is destroyed by people, the organic matter content is extremely low, plants are hard to grow as the soil is short of fertilizer and water, and soil is hard to be repaired and modified according to the conventional physical and chemical repair methods and plant ecological repair methods. The soil improver comprises pigment manure, mushroom residues, bran, humic acid, soybean pulp, water hyacinth, erigeron annuus, a microbial compound inoculant, straws, rice hulls, cow dung, saw dust, brown coal, coconut shells, graphene, a hydrogel and the like. The soil improver can supplement nutrients to soil of the ionic rare earth tailing efficiently, and by combining planting of plants and conversion andabsorption of harmful substances in soil by the soil improver, the soil of the ionic rare earth tailing is repaired stably and efficiently, and the soil repair cost is controlled greatly.