To investigate the influence of fluctuating temperature on the growth and polysaccharide composition of Microcystis aeruginosa, Chlorella pyrenoidosa and Cyclotella meneghiniana were cultured under two temperature patterns:diurnal fluctuating temperature of 20 ± 5℃ and constant temperature of 20℃. In the present experiment we determined the growth curve, growth rate and the content of different polysaccharide compositions. Results show that growth curves of C. pyrenoidosa under two temperature patterns had no significant differences, while those for both M. aeruginosa and C. meneghiniana under fluctuating temperature were significantly inhibited, and the latter suffered the prominently stronger inhibition. As the experiment proceeded, the growth rates for the three algae under the two temperature treatments gradually tend to be no obvious differences, but their responses to the two treatments had significant differences in the middle of experiment. Therefore, temperature fluctuation posed a remarkable inhibitory effect and a short significant inhibitory impact, respectively, to the growth rates of C. pyrenoidosa and C. meneghiniana, whereas it had no obvious effect on M. aeruginosa, revealing that M. aeruginosa showed a stronger ability to adapt to the short term (3-6 d) temperature fluctuation. As for polysaccharide, temperature fluctuation markedly promoted the increase of the soluble extracellular polysaccharide content and decreased the bound polysaccharide content and total polysaccharide content of M. aeruginosa, indicating that temperature fluctuation may not facilitate the bound polysaccharide accumulation of M. aeruginosa. Therefore, relative short-time temperature fluctuation will be in favor of establishing and maintaining M. aeruginosa dominance, but relative long-term temperature fluctuation may benefit C. pyrenoidosa dominance more than M. aeruginosa due to decreased bound polysaccharides of M. aeruginosa.