Abstract:The ultrasonic-assisted extraction process of polysaccharide of Prunella vulgaris L.was studied. Based on the experiment of single factor，the mathematical regression model was established about the dependentvariable（extraction yield ofpolysaccharide）and independent variables（extraction power，extraction temperature，extraction time，ratio of liquid to soild，extraction times）though Box-Benhnken center composite design and response surface methodology.The results showed that the optimum extraction condition were as follow：extracting power of 90 W，extracting temperature was 65℃，the ratio of liquid to solid was 40∶1（mL/g），extracting time of52 min，and extraction times of2.Under these conditions，the practicalyield ofpolysaccharide of Prunella vulgaris L.was 4.60%，which was consistentwith the predicted yield ofpolysaccharide of4.64%.