The application discloses a preparation method for obtaining 1-deoxynojirimycin from mulberry leaves, and mainly solves the problem that the prior art only considers product content and ignores yield, and comprises the following steps: (1)
drying and crushing mulberry leaves, adding water to make pulp, adding
vitamin C after adjusting pH, stirring uniformly, extracting, filtering and centrifuging to obtain a centrifugal liquid; (2) purifying the centrifugal liquid through two-stage OSN organic membrane to obtain a
cut-off membrane liquid; (3) sequentially flowing the
cut-off membrane liquid through more than five cation resin exchange columns in series, first eluting with 1-3 % ml / 100g of
ammonia water, then eluting with 4-5.5 % ml / 100g of
ammonia water, concentrating the eluate collected from the second column to the penultimate column to no
ammonia water to obtain a extract; (4) loading the extract into a mixed
ion resin exchange column, eluting with pure water, and collecting the eluate; (5) making the eluate pass through a
reverse osmosis membrane to obtain a
cut-off liquid, concentrating and
vacuum drying. The method provided by the application reduces production processes and cost, improves product content and guarantees the
recovery rate.