Abstract: Bioconversion of L-phenylalanine to β-phenylethylalcohol with Kluyveromyces marxianus AS2.1440 was performed in an aqueous/organic solvent biphasic system. On the basis of single-factor tests, factors affecting Bioconversion of L-phenylalanine to β-phenylethylalcohol with Kluyveromyces marxianus AS2.1440 were eva luated by Plackett-Burman design, the path of steepest ascent and response surface methodology. The optimal bioconversion conditions are as follows: the concentration of L-phenylalanine was 4 g/L, the optimum values of volume ratio of organic phase to aqueous phase, reaction temperature, pH value and liquid volume were 2 : 3, 32.99℃, 5.0, and 64.46mL/250mL respectively. Under above optimum conditions, the content of β-phenylethylalcohol reached1533±11g/L48 h later, which increased by about 102.91% than that in monophasic aqueous system.