Abstract: The extraction of butyric acid from fermentation broth across microporous hollow fibers to an organic phase and then back extraction to stripping agent was studied. Effects of various factors including the initial pH of butyric acid, the concentration of butyric acid, the flow rate of fermentation broth, organic phase and stripping agent on extraction yield were investigated, and the optimum process conditions were determined by response surface methodology. Results showed that the initial pH of butyric acid had exerted a great influence on the butyric acid separation comparing with other factors. The highest recovery rate of butyric acid was 85.22% when fermentation broth was treated at an initial pH of 2.2 and butyric acid concentration of 74.5mg/mL and the flow rate of fermentation broth, the organic phase and stripping agent were 129mL/min, 90mL/min, respectively.