Abstract: Objective:To optimize the technology of extracting chlorogenic acid from the stem and leaf of dandelion. Method:Using the method of enzymatic ultrasonic combination,cellulase additive amount,enzymolysis time,ultrasonic power and ultrasonic time were chose as the main factors.Based on the single experiments,the extracting processing parameters of chlorogenic acid in dandelion were optimized by response surface method,and the multivariate two regression model was established by the index of the chlorogenic acid yield. Results:The optimum extracting parameters were determined as follows:Cellulase additive amount 0.3%(percentage of dry material),enzymolysis time 1.0 h,enzymolysis temperature 50 ℃,enzymolysis pH4,ultrasonic power 163 W,ultrasonic time 1.7 h,solid-liquid ratio 1:20 g/mL. On this extracting condition,the yield of chlorogenic acid was 2.14%±0.02%,it was similar to the model predictive value 2.12%. Conclusions:The method of enzymatic ultrasonic combination is suitable to extract chlorogenic acid from dandelion,and the extracting technology can be well optimized by response surface method.