Depression is one of the most common psychological disorder in modern society， which seriously affecting both mental and physical health. Currently， long term use of medications for treating depression could result in various adverse reactions. Therefore， there is an urgent need to find new approaches to improve depression symptoms while minimizing side effects. Dietary flavonoids are commonly present in plants and have a positive impact on human health. Several studies have confirmed their significant antidepressant effects. This article provides an overview of the mechanisms underlying depression from six aspects: neurotransmitters theory， neurotrophic theory， neuroinflammatory， oxidative stress， hypothalamic-pituitary-adrenal axis， and the microbiota-gut-brain axis. It elaborates on the formation mechanisms of depression and elucidates how flavonoids can improve cognition and emotions， acting as the main components for alleviating depressive symptoms. This paper serves as a theoretical basis for the development of dietary prevention， as well as the improvement of depression and related functional foods.