The ethanol extraction and membrane separation process of flavonoids from Ginkgo biloba leaves were studied, and the process conditions were optimized as follows: extracting Ginkgo biloba leaves for2 h at 80 °C and ratio of material to solvent 1 : 10 with 70% ethanol, then separated and purified by a gradient membrane device composed of ceramic membranes with relative mol. weights of 30 000, 10 000 and 5 000 under the conditions of the pressure 0. 25 MPa, temperature 30 °C and time 120 min, and the flavonoid transmission rate was 94. 22%, and the content of flavonoids in the product was45. 60% after membrane separation