Citrus fruit is one of fruits with high yield in the world and peel pomace, the mainly byproduct with 20%~40% content in the total citrus fruit, has many application values. In this article, the characteristics and functions of main citrus byproducts, including essential oils, pectin, natural colours, dietary fiber, flavonoids and limonoids, were summarized. Researches on the extraction of those byproducts at home and abroad are reviewed. Some suggestions are made for the processing of citrus in China.