A carbonic anhydrase (CA) transcript was obtained from the Contig library according to the published sequencing information of the buckwheat transcripts. The full length of the CA gene was amplified by reverse transcription PCR (RT-PCR). The bioinformatics analysis showed that the full length of FsCA1 gene was 1233 bp and open reading frame was 978 bp, and encoding 325 amino acids. The molecular weight was 35.11 ku and the isoelectric point was 7.59; there were 9 α helices, 6 β folds, many randon coil and extension chain, containing one signal peptide and one transmembrane region, having a 2 amino acid conserved domains with typical beta-type carbonic anhydrase. Subcellular localization showed that the protein is most likely to appear in the chloroplast. The three-dimensional structure model of FsCA1 was built by homologous modeling method, indicating that the homo-octamer of buckwheat CA and pea CA could match well, so it can be inferred that buckwheat CA is also homo-octamer. Real-time quantitative PCR was used to detect the expression of FsCA1 in different organs of buckwheat. The results showed that FsCA1 had the highest expression level in leaves, then in the stems, and the lowest in roots.