The invention provides an EGCG preparation method, particularly relates to a preparation method for industrial production of high-purity EGCG and belongs to the field of separation and purification of plant monomers. For solving the problem that at present, a process for preparing the EGCG based on an organic solvent extraction method is complicated, adopts a large number of organic solvents in the production process and is not safe and environment-friendly enough, the EGCG preparation method comprises the following steps of green tea smashing, vacuum high-temperature extraction with deionized water, inorganic ceramic membrane filtration, enrichment with macroporous adsorption resin, reversed phase chromatography, vacuum concentration and freeze-drying. The method only adopts water, aqueous ethanol and other solvents in the whole preparation process of the process, the usage and recovery amount of a large amount of organic solvents is decreased, the non-toxic, safe and simple process is achieved, ceramic membrane, resin and reverse chromatographic column filler are recyclable, the cost is greatly reduced, meanwhile the purity of the EGCG is improved, and the process is more suitable for large-scale EGCG production.