Abstract: The root stem of Acanthopanax sessiliflorus( Rupr. et Maxim.) Seem was used as the raw material,ultrasonic assisted extraction of total saponins from Acanthopanax sessiliflorus. The effect of material- to- liquid ratio,ethanol concentration,ultrasonic time,ultrasonic power on the extraction result of the total saponin of Acanthopanax sessiliflorus was studied. On the basis of single factor experiment,Box- Behnken Design was applied to build a regression model,with the yield rate of total saponin as response value. Establish regression model and according to this,the optimal extraction combination was follows: material- to- liquid ratio 1 ∶ 50,ethanol concentration 68%,ultrasonic time 41 min,ultrasonic power 350 W. In this condition,the yield of the total saponin was 1.577%.The true value of the experiment accords with the predictive value of the model was 1.586%,show that response surface center combination method is reasonable and feasible,which can optimize the extraction process of total saponins from Acanthopanax sessiliflorus.