Method for extracting low-caffeine, pesticide-residue-free and ester-free tea polyphenol from tea leaves

The invention discloses a method for extracting low-caffeine, pesticide-residue-free and ester-free tea polyphenol from tea leaves in the technical field of tea polyphenol extraction. The method comprises the following steps of (1) carrying out ultrasonic extraction on tea leaves and distilled water to obtain a leaching solution; (2) soaking adsorption resin in a treatment liquid to obtain treated resin; (3) packing the treated resin into a column to obtain a chromatographic column; (4) eluting the chromatographic column with an ethanol solution to obtain an eluent; and (5) carrying out vacuum concentration on the eluent to recover ethanol, and carrying out low-temperature freeze drying to obtain the target product. According to the method, the adsorbent resin is treated by the treatment liquid, so that trace preservatives and part of residual monomeric compounds in the adsorbent resin are removed, and the purity of the eluent is guaranteed; and according to the method, the chromatographic column is pre-elute