Abstract:In this paper, the preparation of manno-oligosaccharides (MOS) was studies by enzymatic acidolysis. The preparation conditions were optimized by orthogonal experiment and the optimal acidolysis time, enzymatic temperature, HCl concentration, acidolysis temperature, enzyme dosage, and substrate concentration were 1.5 h, 55 ℃, 0.07 mol/L, 85 ℃, 6000 U/g, and 80 g/L, respectively. And the order of their influences was acidolysis time>zymohydrolysis temperature>HCl concentration>acidolysis temperature>enzyme dosage>substrate concentration.