Abstract: The process of bed reactor with immobilized inulin fructotransferase for inulin hydrolysis was founded.The conditions of inulin hydrolysis were explored. Based on single factors experiments,orthogonal experiment was adopted to investigate the influences of inulin concentration,reaction time,reaction temperature and substrate velocity on DFA Ⅲ contents. The optimal conditions were obtained. This process was adopted with the volume of packed bed reactor for 20 m L and loading amount of immobilized enzyme for 15 m L.The best results were attained with inulin concentration 100 g/L,reaction time 1h,reaction temperature 60℃ and substrate velocity 20 m L/h.DFA Ⅲconcentration was 67.38 g/L at the conditions of this process.The process could continue to operate over 48 days.The half-life of operation was 48 days. The foundation was provided for the theory and operation of mass production.