Abstract: Total flavonoids from corncob were extracted using ultrasonic-assisted deep eutectic solvent. Firstly, the extraction solvent composition and component ratio were determined by screening experiment. Then response surface methodology was used to optimize the extraction process. The extraction temperature, liquid-solid ratio, ultrasonic power and extraction time were used as variables, and the extraction amount of total flavonoids was used as response value. The results showed that the optimum extraction process of total flavonoids from corncob with choline chloride/ethylene glycol (molar ratio 1:3) with water content of 30% was as follows: Temperature 61 ℃, 20:1 (mL/g) of liquid-solid ratio, ultrasonic power 137 W, and extraction time 19.5 min, the extraction amount of flavonoids was 4.180 mg/g, with an error of 0.71% compared with the predicted value. The method was proved to be stable and reliable, and could provide scientific data for the development and utilization of flavonoids in corncob.