Lactic acid, as a widely used chemical agent, has received much attention in recent yenrs.Fermentation method was more effective for lactic acid production[1].However, lactic acid fer mentation is well known for its sensitivity with end-product inhibition, which drastically affects cell growth and productivity[2].In order to improve overall process efficiency, the mem brane process was integrated to control the lactate concentration below the toxic level and recycle cells to the bioreactor to obtain high density of biomass at the same time[3,4].