NOVELTY - Extracting high purity puerarin using water as solvent, comprises (i) drying and crushing radix puerariae into crude powder, mixing with water, hot-dipping, filtering, concentrating filtered solution to obtain radix puerariae total flavone extract, (ii) eluting using ethanol, concentrating and recycling ethanol, (iii) decoloring puerarin liquid in aluminum oxide column, vacuum extracting and concentrating, crystallizing and separating out crystal, filtering and drying to obtain crude product, and (iv) crystallizing and precipitating crude product, concentrating and drying.    USE - The method is useful for extracting high purity puerarin using water as solvent (claimed).    ADVANTAGE - The method uses water as solvent to replace organic solvent; extracts puerarin with high purity; solves the problem of production of organic residues, thus reducing the pollution to the environment; has safe and simple processing techniques; and is easy to popularize.    DETAILED DESCRIPTION - Extracting high purity puerarin using water as solvent, comprises (i) drying the root of kudzu vine and crushing into crude powder, mixing with water, hot-dipping at 60 degrees C for 10 hours at a pressure of 1.5 MPa, filtering and collecting the filtered solution, then adding water in a residue, maintaining the same temperature and pressure and hot?dipping for 15 hours, filtering and repeating for 3 times, under the vacuum degree of less than 0.1 MPa, at 45-60 degrees C, concentrating the filtrate to more than 10% to obtain radix puerariae total flavone extract, where the active component extraction rate is more than 90%, (ii) adsorbing radix puerariae total flavone extract by HPD-600 macro-porous resin, eluting, where the first elution is performed by washing off sugar, protein, tannin and water soluble impurities using distilled water, then eluting using 60% ethanol, concentrating the eluent and recycling ethanol to obtain extract to prepare the aqueous solution through AB-8 macro-porous absorption resin column to absorb, using 50% ethanol to elute, collecting eluent and concentrating, then recycling ethanol, (iii) decoloring puerarin liquid in aluminum oxide column, then vacuum extracting and concentrating the filtrate to 50% of the original liquid, allowing to stand the concentrated solution for 24 hours, crystallizing and separating out crystal, filtering and drying to obtain crude product, and (iv) repeatedly crystallizing and precipitating the crude product, concentrating the filtrate and drying to obtain puerarin with purity more than 99%.