Objective: To study the extraction process of flavonoids from gardenia gardenia by ultrasonic-assisted deep eutectic solvent (DES), and to study the hypoglycemic effect of flavonoids on HepG2 cells. Methods: Single factor and orthogonal method were used to optimize the extraction process of gardenia flavone with ultrasonic-assisted deep eutectic solvent. The hypoglycemic effect of gardenia flavone on HepG2 cells in vitro was investigated. Results: The optimal extraction process of flavonoids from gardenia gardenia was as follows: the deep eutectic solvent was choline chloride, the molar ratio of 1, 2-propylene glycol was 1:3, the ultrasonic time was 40 min, the ultrasonic temperature was 60℃, the water content was 20%, the ratio of solid to liquid was 1:33 (g/mL). In addition, in vitro hypoglycemic activity study showed that gardenia flavone has good hypoglycemic activity. Conclusion: This study provides a green and efficient method to extract flavone from gardenia gardenia, and the flavonoid has hypoglycemic activity to a certain extent, which aims to lay a foundation for the industrialization of gardenia gardenia.