Abstract: Response surface methodology was used to optimize the ultrasonic- assisted extraction of total coumarins from Chuanminshen violaceum. Five influencing factors including ethanol concentration, ultrasonic temperature, ultrasonic power, ultrasonic time and liquid to solid ratio were investigated by single factor experiment. On the basis of single factor experiments, a polynomial regression model was fitted by means of Box-Behnken design. The optimum extraction conditions were as follows:60% ethanol, ultrasonic power 140 W, ultrasonic time 49 min, ultrasonic temperature 52℃ and liquid to solid ratio 9∶1 (m L/g) . Under the conditions, the extraction yield of total coumarins reached (2.165±0.017) mg/g. The established regression model was highly significant (R2=0.9864) . The predictive and experimental results were found to be in good agreement. Thus, the model was applicable for the prediction of total coumarins yield.