Quercetin is a natural flavonoid compound widely existing in plants such as Sophora japonica L., Allium cepa L. (onion), and Vitis vinifera L. (grape skin). It is prepared through advanced extraction, purification, and crystallization processes, meeting pharmaceutical grade, dietary supplement grade, or food additive grade standards. While retaining the core biological activities of natural flavonoids, it exhibits excellent antioxidant, anti-inflammatory, and metabolic regulation properties, with low toxicity and good biocompatibility. As a high-value natural active ingredient, it is widely used in the dietary supplement industry, cosmetic field, functional food sector, and pharmaceutical intermediates market.