The chitosan membrane was prepared by the sol-gel freeze-drying method and used to remove the produced vanillin in time from the biotransformation system of isoeugenol to vanillin by Bacillus fusiformis CGMCC1347.The chitosan and vanillin could be linked by the new formed schiff bases.The combining and eluting conditions were optimized.As a result, 1 g chitosan membrane could combine 1.25 g vanillin at pH7.0, 37℃, 200 rpm in 48 h.All the combined vanillin could be eluted from the chitosan membrane with 6.17%(v/v) HCl at room temperature in 10 h.The product inhibition could be avoided by the addtion of chitosan membrane during the biotransformation.The optimal biotransformation conditions were isoeugenol 2% (v/v), wet cells 0.48 g, chitosan membrane 0.1 g, phosphate buffer (pH 8.0) 50 mM, 37℃, 180 rpm for 60 h in 20 mL reaction liquid in 50-mL flask and the highest concentration of vanillin reached 1.71 g/L.