The invention discloses a method for extracting total flavonoids from
hibiscus manihot. The method comprises the following steps: (1) extracting, wherein an
ethanol solution having the
mass concentration of 40-99% is used as an extraction solution and a
hibiscus manihot total
flavonoid extract is obtained by virtue of
microwave extraction; (2) purifying, namely enabling the
hibiscus manihot total
flavonoid extract to sequentially pass through hollow
fiber ultrafiltration membranes having the molecular weight cutoffs of 10000-50000Da and 2000-6000Da and collecting penetration liquid; next, concentrating the penetration liquid by use of a
nanofiltration membrane having the molecular weight cutoff of 100-500Da, thereby obtaining a hibiscus manihot total
flavonoid concentrated liquid; (3) refining, namely adsorbing the hibiscus manihot concentrated liquid by use of a macroporous adsorption resin, orderly performing
water washing and
alcohol washing, and performing freeze-
drying to obtain the hibiscus manihot total flavonoids. Compared with the prior art, the technology of the method is capable of greatly increasing the hibiscus manihot total flavonoid
extraction ratio, and also capable of reducing the content of macromolecular saccharides and
protein in the product, reducing the content of
metal ions and inorganic salt in the product and improving the product purity.