Abstract: The purpose of this study was to hydrolyze PE for oligosaccharide using specific PE degradase. The enzymatic hydrolysis conditions were optimized. The saccharide composition of the hydrolysate fractions was analyzed by liquid chromatography and electrospray ionization mass spectrometry.The yield of reducing sugar was chosen as an evaluating indicator during single factor experiments and response surface methodology. Results showed that the enzyme could hydrolyze PE efficiently. The optimal hydrolysis condition was as follows: enzyme dosage 1.5%,substrate concentration 14 mg / m L,the initial p H6.5,reaction time 6 h,and hydrolysis temperature of33 ℃.The corresponding reducing sugar yield and hydrolysis efficiency was 165.21 mg and 61.21%,respectively.Besides,the viscosity of PE reduced from 349.89 m Pa·s to 2.05 m Pa·s.The HPLC results indicated that the monosaccharide composition of the hydrolysate was rhamnose,glucuronic acid,glucose and xylose.The results of mass analysis showed that degradase could degrade sulfate PE and neutral PE.