The isoeugenol aqueous biphasic system was developed successfully for effective transforming isoeugenol to vanillin by Bacillus fusiformis CGMCC1347,which had high tolerance of isoeugenol and was(isolated) by screening and selection from soil.Under isoeugenol concentration of 60%,the bacteria was cultured at initial pH 4.0,37 ℃,180 r/min for 72 h,the cell density reached 60 g/L,while the content of vanillin reached 46.10 g/L.