The greenhouse effect, which is believed to occur primarily as a result of the accumulation of carbon dioxide in the atmosphere, has become one of the major environmental concerns and received worldwide attention. In this paper, algae species screening and cultivation for efficient CO2 fixation are reviewed. The related dissolved inorganic carbon (DIC) utilization form and CO2 concentration mechanism (CCM) in the process of CO2 fixation by microalgae are analyzed. Four objectives of the highly effective photobioreactor design and operation are discussed, and the advances on CO2 mitigation technology with integration of microalgae (enzyme) and membrane bioreactor are also briefly introduced. In response to elevated CO2 concentration, much attention needs to be paid to the construction of transgenic microalgae with higher performance in CO2 fixation based on the further ascertainment of the related mechanism, and the development of effective CO2 biofixation system integrated with other kinds of advanced technology, such as membrane immobilization and separation.