Abstract:Response surface methodology（RSM）was used to optimization of ethanol precipitation of polysaccha－ rides from Portulace oleracea L..Based on the single factor analysis， the effect of centrifugal time， the centrifu－ gal rotational speed and solid-to-alcohol ratio on polysaccharides from Portulace oleracea L. was evaluated by response surface analysis. Three factors， three levels central composite experimental design was applied and the interactions of each factor on the polysaccharides from Portulace oleracea L. were also investigated. The centrifugal rotational speed and solid-to-alcohol ratio had significant effects on extraction yield. The optimal conditions of polysaccharides in Portulace oleracea L. alcohol sinking process were as follows：the liquid-to-al－ cohol ratio was 1 ∶ 4（mL/mL），centrifugal time was 10 min， and the centrifugal rotational speed was 3 800 r/min. Under such conditions， extraction of the polysaccharides yield was 9.5 %.