Abstract: The flavonoids in Citrus are the most common type of polyphenols in nature. They are the secondary metabolites of plants. They have many beneficial physiological effects to the human body, such as antioxidant, anti-cancer, anti-inflammatory, anti-bacterial, and anti-aging. This review introduces the types of flavonoids in Citrus and a variety of effective extraction methods including solvent extraction, supercritical fluid extraction, ultrasonic assist, and enzymatic extraction. And on this basis, the research progress of its anti-oxidation, anti-inflammatory, antibacterial, anti-aging and other physiological functions, as well as the latest applications, etc. are investigated and summarized, in order to provide references for the in-depth development and comprehensive utilization of Citrus flavonoids.