The invention discloses a method for extracting aucubin from folium cortex eucommiae, aucubin powder is prepared by crushing of the folium cortex eucommiae, cellulase assisted extraction in medium temperature water, conventional filtration, impurity removal by a ultrafiltration membrane, nanofiltration concentration, separation and purification by macroporous resin, concentration and drying; according to the method, the aucubin is extracted from the folium cortex eucommiae by cellulase assisted extraction in the medium temperature water, the extraction rate can reach 95%, the water extraction temperature is lower, and the extraction time shorter; the ultrafiltration membrane is used for impurity removal of an extracting solution, and separation of other by-products, the membrane operation process is simple, the membrane flux can be stable for a long time, the membrane is easy to clean and long in service life and realizes industrialization; an nanofiltration membrane is used for concentration of the impurity removed extracting solution, the load of follow-up processes can be reduced, and the service life of resin is lengthened; the COD value of a nanofiltration filtrate is less than or equal to 100, the nanofiltration filtrate can be reused in the production process, and basically no waste water is not discharged; the macroporous adsorption resin can effectively purify the aucubin, purity of the aucubin in the prepared powder is greater than 62%, and the extraction rate is more than 2.8%.