Enzyme has been modified to make it less sensitive to physical and chemical factor. Because of the high price of enzyme, effective and economic recovery method is needed. In this study, aqueous two phase system using hydrophilic PEG polymer and photassuim phosphate was applied to recover the modified enzyme. The system with dibasic/monobasic phosphate mole ratio = 1.42 were mixed with appropriate amount of 10% PEG solution. Most enzyme, approximately over 70%, moved to polymer phase. Partition coefficient was also defined and used to estimate the mobility of modified enzyme.