Abstract:This paper focused four factors and their interactions on the impact of extraction of polysaccharide from Allium sativum L.， while based Design-Expert software design， optimization conditions of polysaccharide extraction， in order to provide the basis for the development and utilization of polysaccharide. Using Design-Expert software for the four factors and three levels Box-Behnken experimental design， the polysaccharide ex－ tracted with hot water extraction and alcohol precipitation， the method of phenol -sulfuric acid to detect the polysaccharide content. Meanwhile， extraction time， solid-liquid ratio， extraction temperature and extraction times were investigated on the impact of polysaccharide yield. On the basis of single factor experiments， using Design-Expert software for the four factors and three levels Box-Behnken experimental design， a mathematical model of polysaccharide textraction rate and various factors were created. The results showed that the extraction temperature， ratio of water to marterial， extraction time and extraction times， individual quadratic interaction term and its impact on the polysaccharide yield significantly， while the interaction term of liquid ratio and ex－ traction time， liquid ratio and extraction times were not obvious. Polysaccharide extract optimum conditions eventually identified as： extraction temperature 81 ℃， ratio of water to marterial 14 ∶ 1（mL/g）， extraction time 84 min and extracted times was 2.