Abstract: Under natural conditions, the hydration of CO₂ is an extremely slow reactive progress. However, carbonic anhydrase (CA), a metalloenzyme combining with Zn²⁺ at its active centers, could reversibly accelerate the conversion between CO₂ and carbonic acid. Although highly efficient and environmental safe in theory, it still faces difficulties for large-scaled application such as instability and low activity under complex environmental influences such as temperature, pH and other solvents. There is not an ideal CA biocarrier, plus high cost in production and high difficulty in immobilization. There is active research into resolving all these issues related to CA. At present, Chitosan, inorganic nanoparticles, mesoporous materials and polyurethane foam are widely used as the carriers for CA immobilization; when they are well bonded, they perform better than the free ones. For example, silicon nanoparticles are characterized by high temperature resistance. The common approaches of binding CA includes covalent attachment, adsorption and cross-linked aggregation. Among them, covalent attachment could solve the leakage of CA in operation. Researchers have been working on reaching the goal for CA's industrial application, and they have made some progress. For instance, they select heat-resistant bacteria or directly express the CA protein in high temperature environment; mix CA with other CO₂ dissolving solvents like amine, MEA, MEDA; use polysulfone humidifier to ameliorate the volatility of liquid membrane; and add Ca(OH)2 or employ ion exchange facility to decrease the amount of HCO₃^- in the reaction.