[Background] Carbonic anhydrase has become the hotspot in carbon reduction research due to its ability to efficiently convert CO2 to HCO3－. Because of the flue gas high temperature, searching for thermostable, the thermophilic carbonic anhydrase is the key to achieve the biomimetic capture of CO2 in industrial flue gas. [Objective] The carbonic anhydrase (CAH) gene of Thermosynechococcus elongatus PKUAC-SCTE542 (Ecah) and Synechococcus lividus PCC6715 (Pcah) were cloned and expressed in Escherichia coli, and the enzymatic properties were characterized. [Methods] The two genes of the CAH were amplified by PCR. The recombinant plasmid pETM11-ECAH, pETM11-PCAH was overexpressed in BL21(DE3) pLysS by IPTG induced. The recombinant carbonic anhydrase was purified with Ni-Agarose His-tagged affinity chromatography and the enzymatic properties were further checked. [Results] Two length of 534 bp carbonic anhydrase were both obtained from E542 and PCC6715. The CO2 hydration activity of the ECAH and the PCAH was 42.6 WAU/mg-protein, 47.6 WAU/mg-protein, respectively. After 50 °C incubation for 30 min, the ECAH activity was increased by 8%, but the PCAH was decreased by 10%. The ECAH activity was increased to about 108% after treated by Ca2+ for 30 min, but no significant inhibition of PCAH activity was observed. Both the ECAH and PCAH activities were significantly inhibited by Zn2+ and sulphanilamide. [Conclusion] The ECAH of the Thermosynechococcus elongatus PKUAC-SCTE542 showes favorable thermostability than PCAH of the Synechococcus lividus PCC6715. EACH meets the basic requirements for CO2 treatment of industrial high-temperature point source flue gas, and enriches the thermophilic carbonic anhydrase gene pool.