The blue-green algae is one kind of the important components of phytoplankton in waterbodies. It is also the main primary producer of freshwater and marine ecosystems. In recent years, with the increase of CO_2 emission to atmosphere, the global climate is changing significantly. The frequent extreme weather events exert great impact on the concentration of dissolved organic carbon in waterbodies, as a consequence, CO_2-concentrating mechanism (CCM) of algae is affected. Through CCM, the concentration of CO_2 could be increased located at RubisCO of the algae cells, in order to promote the photosynthesis and diminish light respiration of algae. Based on the climate change due to the increase of CO_2 concentration, the equilibrium among inorganic carbon in different forms in open waterbodies was first described in this review. The carbon recycling processes in waterbodies and their effect on the algae was then analyzed. Various experimental simulation technology of the elevated inorganic carbon concentration in the environment as well as the research method of the algae growth and species competition with the elevated CO_2 concentration were also summarized.According to the researches on the CCM of blue-green algae, inoraganic carbon enter the blue-green algae via the Calvin Cycle. Under the catalysis of carbonic anhydrase, HCO_3~- and CO_3~(2-) as the form of inorganic carbon could be transformed into CO_2, which increases the CO_2 concentration around RubisCO and the inorganic carbon utilization efficiency of algae. However, CCM of algae is also affected by pH, illumination, nitrogen and phosphorus, etc. Based on this theory, the effect of inorganic carbon on the cell structure, size and the individual cell proliferation of blue-green algae was summarized.Some researchers indicated that CO_2 with high concentration could promote the growth of nuclear protein of algae cells, and this phenomenon is much significant for the algae cells with small size. Since the CO_2 could be directly utilazed by blue-green algae, CO_2 play a more important role on promoting the reproduction of individual algal cell proliferation. The pH of natural surface water is in the range of neutral to weak alkaline. Therefore, there are more researchers focus on the CO_2, HCO_3~- utilization by blue-green algae and their CCM. In summary, although there are a great number of studies on the effect of climate change, the factors such as the mechanisms of carbon utilization, the micro-changes in the cell and the CCM of blue-green algae during the algal growth and bloom still need to be further studied.