Degenerate primers designed from the conservative domain of Chalcone Synthase(CHS) in plants were used to amplify the CHS fragments from genomic DNA of tartary buckwheat(Fagopyrum tataricum Gaertn.) cultivar 'Xinong 9920' and common buckwheat(Fagopyrum esculentum Moench) cultivar 'Xinong 9976';A single 860 bp fragment was amplified from both tartary buckwheat and common buckwheat,respectively.The amplified fragments were then collected,cloned and sequenced.Sequence analysis indicated there was the typical domains of N-terminal and C-terminal of CHS in those two fragments,designated as FtCHS and FeCHS for tartary buckwheat and common buckwheat,respectively.Comparison on the nucleotide sequence of FtCHS and FeCHS revealed 43 single nucleotide polymorphisms,which may be one of the major reasons leads to the difference of flavonoids contents in seeds between tartary buckwheat and common buckwheat.Phylogenic analysis on the amino acid sequence of CHS from tartary buckwheat and common buckwheat with some other plants showed that tartary buckwheat and common buckwheat were closely related to Rheum palmatum and Gypsophila paniculata.