Flavonols, also known as 3-hydroxyflavones, are a kind of unique flavonoids that widely distributed in the plant kingdom, and have been associated with a wide variety of biological activities and pharmaceutical applications. Four principal synthetic approaches to flavonol skeleton including Auwers synthesis, Algar-Flynn-Oyamada reaction (AFO), Baker-Venkataraman synthesis and flavone oxidation by 3,3-dimethyldioxirane (DMDO) are summarized. The regioselective methylation, prenylation and glycosylation of polyhydroxyl flavonols are presented as well.