NOVELTY - Separation and preparation of Lithocarpus polystachyus phlorizin monomer involves clarifying L.polystachyus extract with microfiltration membrane, adding filter solution to pure water, dialyzing, combining the filtrate and dialyzate, filtering supernatant liquid, adding supernatant solution to pure water, dialyzing, combining filtrate and dialyzate, filtering, concentrating separated liquid, diluting the concentrate with pure water, loading obtained liquid on ADS-7 macroporous resin, eluting, concentrating the eluate, filtering, crystallizing, and freeze-drying.    USE - Separation and preparation of L.polystachyus phlorizin monomer (claimed).    ADVANTAGE - The method enables economical separation and preparation of L.polystachyus phlorizin monomer with high yield and quality, by safe, simple and environmentally-friendly process.    DETAILED DESCRIPTION - Separation and preparation of L.polystachyus phlorizin monomer involves washing L.polystachyus, drying, clarifying L.polystachyus extract with microfiltration membrane having pore size of 0.2 mu m, obtaining filter solution and filtrate, adding obtained 80-90 wt.% filter solution to 10-20 wt.% pure water, dialyzing, combining the filtrate and dialyzate, filtering supernatant liquid using ultrafiltration membrane having molecular weight cutoff of 2500 Da, obtaining filtrate and supernatant solution, adding 80-90 wt.% supernatant solution to 10-20 wt.% pure water, dialyzing, combining filtrate and dialyzate, performing ultrafiltration process, concentrating separated liquid under reduced pressure, recycling drinkable alcohol, diluting the concentrate with 1-1.5 times of pure water, purifying with ADS-7 resin, loading obtained 4-6 BV obtained liquid on ADS-7 macroporous resin at flow rate of 2-3 BV/hour, aging for 30 minutes, rinsing resultant product with 2 BV 20-40% edible ethanol, eluting with 2-4 BV 70-90% ethanol at flow rate of 1.5-2.5 BV/hour, concentrating the eluate under reduced pressure, recycling drinkable alcohol, filtering the concentrate while hot, crystallizing, and freeze-drying under vacuum.