The crude extraction liquid of traditional Chinese medicine contains extremely complex multicomponent mixtures after water extraction or alcohol extraction, including target active pharmaceutical ingredients, macromolecular colloids, residual plant fibers, tannins, inorganic salts, heteropolysaccharides and pigment impurities. Traditional refining technologies such as alcohol precipitation, resin adsorption and vacuum thermal concentration are difficult to achieve precise impurity removal, and usually cause problems such as active ingredient loss, low purification accuracy, high energy consumption, solvent residue and unstable batch quality. In modern standardized Chinese medicine pharmaceutical production, higher requirements for clarity, safety, stability and efficacy consistency have gradually eliminated outdated traditional processes. Cross-flow nanofiltration membrane separation technology relies on dual mechanisms of molecular weight screening and charge repulsion to realize low-