Abstract: The red bean starch was disassembled by enzymolysis function of saccharifying enzyme to solve the problem of poor solubility of red bean powder in the research. With viscosity for index, the best enzymolysis condition of the saccharifying enzyme was optimized by single factor and orthogonal experiment in the research.The results showed the viscosity of preparative red bean pulp was 1425 m Pa·s at enzyme solution temperature60℃, enzymolysis time 4h, p H5 and quantity of enzyme 300 U / g. The instant of red bean powder was improved effectively.