Abstract: Carbonic anhydrase (CA) is an enzyme that catalyzes the formation of carbonic acid from carbon dioxide and water. In order to explore the role of CA in the calcification process of Capitulum mitella shell plate, the members of CA gene family of Capitulum mitella were identified by using the bioinformatics method, and their physicochemical properties, subcellular localization, secondary structure, tertiary structure, conserved motifs, chromosomal localization, transmembrane structure prediction and evolutionary relationship of the encoded proteins were analyzed. Then, combined with transcriptome analysis, the expression patterns of CmCA in different developmental stages were also analyzed. The results showed that 10 CA gene family members were identified in the Capitulum mitella genome, which were distributed on six different chromosomes. The analysis on the basic physicochemical properties of the protein encoded by the CA gene family members of Capitulum mitella showed that the number of amino acids of the protein ranged from 108 to 318, with the relative molecular mass of the protein between 12.10 kDa and 36.22 kDa, and the isoelectric point coefficient between 5.09 and 10.68, all of which were hydrophilic proteins. The phylogenetic analysis showed that CmCA3, CmCA4 and CmCA5 were clustered into one branch, while CmCA6, CmCA7, CmCA8 and CmCA9 were clustered into another branch. Meanwhile, CmCA1, CmCA2 and CmCA10 were clustered into independent branch, respectively. The transcriptome data analysis showed that the expression levels of CmCA7, CmCA8, CmCA2, CmCA6, and CmCA10 were relatively low at the stage of nauplius larvae, while CmCA5 and CmCA3 had higher expression levels during the metamorphosis mid-stage and juvenile stage, respectively. CmCA4 and CmCA1 had high expression levels at the stage of nauplius larvae. The expression of CmCA9 increased in the 5th stage of Venus larvae, and then decreased significantly. In summary, the results provided a theoretical basis for the further analysis of the regulatory mechanism of CA gene in the calcification process of Capitulum mitella shell plate.