Abstract: Ultrafiltration technology was used to concentrate the β-amylase from the soybean whey wastewater which displays high β-amylase activity. The optimization of the UF process which involved the selection of membrane molecular weight cut off (MWCO) , operating temperature and the pH of the feed was studied. Experiment results showed that polyethersulfone membrane with molecular weight cut off (MWCO) 3ku could be applied to enrich the β-amylase signally at trans-membrane pressure (TMP) :2bar;pH7. 0, 25±3℃, the flux decreased from 44L/ (m2·h) to 23L/ (m2·h) , got an average flux of 35L/ (m2·h) . The β-amylase in the retentate got an activity of 101U/mL with 92% yield, with a volumetric concentration ratio of 10 times, and the concentration ratio of enzyme activity was about 9 times. β-amylase in the retentate with a relatively high activity, which provided a good foundation for the further purification of the β-amylase. Meanwhile, this technology provided a new thought to make good use of the soybean whey wastewater for the Chinese manufacturers.