The invention relates to a method for comprehensively extracting active substances from
asparagus scraps based on multi-stage membrane separation, which comprises the following steps that: the
asparagus scraps are used as a
raw material, are extracted with hot water of PH = 7-9 to obtain an extract, and then the extract is subjected to
sedimentation centrifugation and 100-800-mesh bag filtering; the extract is subjected to an
ultrafiltration membrane with interception molecular weight of 5000-15000Da to obtain a concentrated solution and a filtrate, the concentrated solution is precipitated with 75-95%
alcohol to obtain an
asparagus polysaccharide precipitate, and the asparagus
polysaccharide precipitate is separated and dried to obtain asparagus
polysaccharide with the content of 50%; the obtained filtrate is concentrated with a
nanofiltration membrane with the molecular weight of 100-500Da to obtain a concentrated solution, the pH value of the concentrated solution is adjusted to 3-4, the concentrated solution is precipitated and dried to obtain
rutin; and finally, a dialysate is pumped back to an extraction tank to be used as water for extraction. The residues are crushed to be used for feed. The process adopts an advanced membrane
separation technology, improves the preparation efficiency of asparagus polysaccharide and
rutin, realizes clean production and no waste water and residue emission, turns waste into wealth and realizes comprehensive utilization of resources. The method has the advantages of advanced process, stable product quality, high purity, clear target and easiness in industrial production.