The invention discloses a method for preparing 3-hydroxy butyrate, and relates, and relates to the technical field of chemical synthesis and comprises the following steps of: adding an aluminum-nickelalloy catalyst into ethyl acetoacetate, carrying out acyl hydrogenation reaction at the temperature of 40-100 DEG C under a normal pressure, and carrying out suction filtration after the reaction isfinished to obtain 3- hydroxyl butyrate ethyl; dissolving the 3-hydroxybutyrate ethyl in water, adding inorganic base for reaction, decolorizing with activated carbon after reaction, filtering, concentrating the filtrate, crystallizing, and drying to obtain the 3-hydroxy butyrate. The method has the advantages of short reaction steps, cheap and easily obtained raw materials, mild reaction conditions, no need of pressurization, simple and safe operation and low requirement on production equipment; the adopted aluminum-nickel alloy catalyst is simply and easily obtained, can be recycled and reused, the production cost can be better controlled, the prepared product has high purity, the yield is high and the cost advantage is obvious, and the method is suitable for industrial production.