Abstract: The use of photosynthetic microorganisms to capture CO₂ is a promising method for reducing CO₂ emissions. However, the short residence time of CO₂ in culture medium and the difficulty of conversion into dissolved inorganic carbon limit the growth and carbon fixation of algae cells. In this study, the CO₂ adsorbent was prepared by calcining the zeolitic imidazolate framework (ZIF-8) for various time. Flue gas CO₂ from coal-chemical industry could be adsorbed on the unsaturated metal sites and converted into HCO₃^-, providing sufficient carbon source for the growth of cells. The CO₂ adsorbent obtained by calcining for 6 h performed best due to the largest specific surface area and pore volume, which were conducive to the adsorption and conversion of CO₂. The HCO₃^- concentration in culture medium increased by 55.7%, resulting in a 2.43-fold increase in the light energy utilization efficiency of Arthrospira platensis under 99.99% CO₂ conditions. The cultivation time was shortened from 7 days to 5 days, and finally the biomass yield and the CO₂ fixation rate were enhanced by 74.7% and 93.7%, respectively.