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With the aim to take full advantage of coumarin in cassava peel, the extraction technology of total coumarin was first researched from cassava peels by ultrasonic-assist. The optimal extraction technology condition of total coumarin was determined by the single factor experiment and Box-Behnken design test. The results indicated that the optimal extraction conditions were as follows: ethanol concentration 95%, ultrasonic power 550W, ultrasonic extraction time 90min, and ultrasonic extraction temperature 60℃, liquid-solid ratio 12mL/g. Under the optimal extraction conditions, the average content of total coumarin in avtive extraction was 2.48mg/g.The effect sequence of four main factors for the content of total coumarin are as follows: ultrasonic power, extraction temperature, extraction time, liquid-solid ratio. Compared with the traditional solvent extraction, ultrasonic extraction has obvious advantages including the higher content of total coumarin, faster extraction speed, good activity extracts, less solvent and etc.