Abstract: A method on the separation and extraction of L-methionine(Met),L-leucine(Leu),L-phenylalanine(Phe),and L-tryptophan(Trp),using a strip dispersion hybrid liquid membrane(SDHLM) containing di-(2-ethylhexyl) phosphoric acid(D2EHPA) with kerosene as the organic liquid membrane phase and HCl solution as the aqueous strip solution,is developed.The effects of pH in the feed solution,the concentration of the carrier(D2EHPA),the volume ratio of the organic liquid membrane solution to the aqueous strip solution,the strip solution composition,the flow rates of the feed solution and the strip dispersion phase,the extraction time,and reuse times of the support membrane on the permeability coefficient and the transport efficiency of amino acids were investigated.Under the optimal conditions,the transport efficiencies obtained for the four amino acids,Met,Leu,Phe,and Trp were all higher than 35%,and more than 79% of transport efficiencies were obtained for Leu and Trp.The transport efficiency exhibits a trend of E_t,Trp >E_t,Leu >E_t,Phe >E_t,Met.With the 12 h-extraction time,the support membrane could be reused for at least 25 times with little decrease in the transport efficiency of amino acids.The developed method with high transport efficiency and excellent transport selectivity for the studied amino acids is simple and environmental friendly.