Carbon capture and resource utilization are of great significance to alleviate environmental problems such as global warming and glacier melting, and it is one of the effective ways to achieve carbon neutrality. The conventional CO2 capture way by chemical absorption has the problem of high energy consumption. Due to the low solubility of CO2 in the medium, CO2 escape is often caused when fixed by microalgae, then resulting in low carbon fixation efficiency and secondary CO2 emissions. Chemical absorption and microalgae conversion hybrid system has the potential advantages of reducing renewable energy consumption and improving CO2 resource utilization.Ammonia was used as a chemical absorber, and NH4HCO3 generated after fully absorbing CO2 partially replaced NaNO3 in the process of traditional microalgae culture. In order to reduce the toxicity of high concentration NH+4-N to Spirulina and further reduce the nitrogen source cost of the coupling system, the nitrogen source composition was optimized by batch addition of NH4HCO3. Results shows that batch addition of NH4HCO3 can reduce the required total nitrogen content and promote the synthesis of lipid without affecting the growth of Spirulina. When 50 mg/L NH4HCO3 is added every 6 days, the nitrogen fixation rate and carbon fixation capacity are the highest, which are 32.33% and 149.24 mg/(L·d), respectively, and the maximum biomass is 1.30 g/L on the 12th day. In addition,the components of Spirulina in the coupling system are affected by different feding-batch modes. Supplementation of 50 mg/L NH4HCO3 every 6 days is beneficial to the production of protein, which reaches 889.17 mg/L. Adding 75 mg/L NH4HCO3 every 6 days is conducive to the accumulation of carbohydrates in Spirulina, reaching 1 632.86 mg/L. This study provides guidance for the further application of the chemical absorption and microalgae conversion hybrid system by batch feeding mode, and has the potential and application prospects.