Abstract: The discarded stems and leaves of Apium graveolens are rich in natural chlorophyll, and extraction of chlorophyll from abundant Apium graveolens stems and leaves can not only alleviate the shortage of chlorophyll resources but also be beneficial for environmental protection. The chlorophyll was extracted by the method of organic- solution with the ultrasonic- assisted treatment and the Box- Behnken design combined with single factor experiments was used to optimize ultrasonic- assisted extraction of chlorophyll.The results showed that the optimal technological parameters were as follows, liquid to solid ratio of 20 m L / g for 75 min at 50℃. Under these experimental conditions, the predicted chlorophyll content was 9.796 mg / g, the verification extraction yield was9.629 mg / g.