The invention relates to a preparation method of high-purity maltose and beta-limit dextrin. The preparation method includes the steps of firstly, preparing starch milk; secondly, gelatinizing the starch milk, and adding beta-amylase to perform saccharification reaction to obtain a saccharification product; performing decoloration and deproteinization on the saccharification product, and desalting and concentrating to obtain a concentrated product; fourthly, subjecting the concentrated product to chromatographic separation to obtain maltose and beta-limit dextrin; fifthly, subjecting the maltose to decoloration hybridization, concentration and drying refining to obtain the high-purity maltose; sixthly, subjecting the beta-limit dextrin to decoloration hybridization, concentration and drying refining to obtain the low-DE-value beta-limit dextrin. The preparation method has the advantages that the maltose and the beta-limit dextrin are generated under the effect of the beta-amylase after the gelatinization, separation is benefited, and the high-purity maltose and the low-DE-value beta-limit dextrin are obtained.