The species that can make full use of cassava alcohol wastewater and CO2 exhaust gas to grow were screened from four common species of common Microalgae, and the effects of CO2 concentration on their growth and ability to remove total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (CODcr) in wastewater were investigated. The growth of Microalgae was judged by the change of dry weight and chlorophyll a (Chl-a) content in wastewater, and the most suitable Microalgae was selected. Through single factor test, the effects of different CO2 mass concentrations on the dry weight, Chl-a content and fixed rate of CO2 of selected Microalgae were studied to find the most suitable concentration for growth. The purification effect was evaluated by measuring the changes of TN, TP and CODcr in wastewater. Screening test showed that Spirulina platensis could adapt to the growth environment of alcohol wastewater and CO2 exhaust gas. In 100% alcohol wastewater, the dry weight and Chl-a content of S. platensis were significantly higher than those of Oocystis borgei, Chlorella vulgaris and Scenedesmus quadricauda (P < 0.05). The single factor test showed that when 2.5% CO2 was added, the dry weight of S. platensis cultured in alcohol wastewater was (1.62±0.05) g/L, and the Chl-a content was (12.1±0.7) mg/L, both significantly higher than those in other test groups (P < 0.05). Meanwhile, the removal rates of TN, TP and CODcr in alcohol wastewater were (50.5 ± 2.1)%, (73.2 ± 2.0)% and (24.9±0.6)% respectively. S. platensis could adapt to the growth environment of alcohol wastewater and absorb CO2 exhaust gas, with good purification effect. The most suitable CO2 mass concentration for its growth is 2.5%.