Abstract: In this work,soybean whey proteins' removal experiments were conducted using a ceramic ultrafiltration( UF) membrane with the average pore size of ca.5 nm,and effects of different operating conditions on separation performance were investigated. Additionally,the cake-complete model was employed to explain the ultrafiltration fouling mechanism. Results showed that the maximal permeation flux of 6.85 L·m~- 2·h~- 1was achieved under0.15 MPa. When the pressure were increased from 0.15 to 0.20 MPa,the concentration polarization dominated,resulting in the diminishment of effective driving force and thus the flux were not increased significantly with increasing pressure.Besides,the rejection rate of whey protein could be adjusted by p H of solution and be up to73.3% at p H6.Moreover,the best fitting result was obtained by using the cake-complete model,the fitting degree calculated was above 0.99,which suggested that the membrane fouling process was not controlled by individual mechanism and resulted from combined effects of diverse fouling types. Therefore,these results may provide a significant inside into the industrial separation of whey proteins.