S-licarbazepine was synthesized by asymmetric reduction of oxcarbazepine in organic solvent/phosphate buffer biphasic system with Bacillus anthracis CGMCC No.12337 as catalyst. Effects of many factors on reduction were studied. Dibutyl phthalate/phosphate buffer was selected as the optimal biphasic system for reduction. The optimum reduction conditions are as follows: volume ratio of dibutyl phthalate and phosphate buffer 1:1, 30 g/L iospropanol as co-substrate, phosphate buffer pH 5, substrate concentration 7.92 mmol/L, cell concentration 30 g/L, 32°C，180 rpm. The conversion and enantiometric excess of S-licarbazepine reached 97.32% and 99.80%. An efficient method for synthesis of S-licarbazepine was provided.
