Abstract: The permeation experiments of L-phenylalanine and L-aspartic acid aqueous solution were carried out with NTR7450 membrane. When pH=5~8 the rejections to L-phenylalanine and L-aspartic acid by NTR7450 membrane are about 0 and 90%, respectively. The concentration and separation process of phenylalanine and aspartic acid solution was simulated. The results showed that L-phenylalanine and L-aspartic acid can be separated satisfactorily by adjusting the pH value.