The invention belongs to the field of aluminosilicate compounds, and in particular relates to a method for preparing a 4A molecular sieve from bauxite tailings. The preparation method comprises the following steps of: (1) iron removal by using an acid process; (2) congruent melting of tailings and alkali; (3) solution preparation; (4) crystallization reaction; and (5) washing. According to the preparation method, the 4A molecular sieve which is suitable for a detergent builder is prepared by taking bauxite milltailings as a raw material, the raw material is abundant in source, and the production cost of the 4A molecular sieve is reduced; and meanwhile, the environment problems caused by low utilization rate and long-term disposal of the bauxite tailings are solved, the utilization rate and the additional value of the bauxite tailings are increased, and a new approach is opened up for comprehensive utilization of the bauxite tailings.