Abstract: The effects of light quality and CO₂ concentration on the growth and the contents of nitrogen and phosphorus of two microalgae (Dicrateri.zhanjiangensis and Dunaliella sp.) in the 600 L air-lift photobioreactor systems that designed by oneself were investigated. The results showed that the effects of interior illuminant of different light qualities on microalgae were different. Dicrateri.zhanjiangensis and Dunaliella sp. both reached their maximum biomass in red, blue light and red, white light separately, and their nitrogen contents increased in the interior light sources, but all the interior illuminant had no effect on their phosphorus contents. By supplying high density of CO₂(above 700 μL·L^-1) in photoreactor, the biomass of two microalgae could increase apparently, and their nitrogen and phosphorus contents were significantly increased in high CO₂ concentration (above 700 μL·L^-1) compared with low CO₂ concentration(350 μL·L^-1). The microalgae cultivated by using this technolege grown quickly and the output of which was steady. The result of pilot scale reasearch can provide groundwork for the popularization use of this technology.