As the eutrophication of freshwater system becomes an increasingly widespread phenomenon during the last few decades, toxic Microcystis blooms are occurring all over the world. Therefore, the water supply security and human health are threatened because some Microcystis stains can produce malodorous compounds and microcystin. Microcystis blooms in natural freshwater system are usually caused by the combination of toxic and non-toxic Microcystis species. Furthermore, climate warming is thought to lead to the expansion of these blooms. To investigate whether the competitive ability of toxic M. aeruginosa FACHB-905 is higher than the non-toxic ones under global warming background, we studied the growth, photosynthesis and light resistance of non-toxic M. aeruginosa FACHB-469 and toxic M. aeruginosa FACHB-905 after they had been cultured for 10 days at temperatures ranged from 15 to 40 ℃. The results showed that both non-toxic M. aeruginosa FACHB-469 and toxic M. aeruginosa FACHB-905 grew little at 15 ℃ and could not survive for a long time at 40 ℃. However, the average specific growth rate of both strains increased with increased temperatures ranged from 20 to 30 ℃, and then began to decrease when temperature was further increased to 35 ℃. Moreover, the specific growth rate of toxic M. aeruginosa FACHB-905 was slightly higher than that of non-toxic M. aeruginosa FACHB-469 at temperatures ranged from 20 to 35 ℃ though the difference was not statistically significant. However, the maximal photosynthetic rate (P_(max)) and dark respiration (R_d) of toxic M. aeruginosa FACHB-905 were significantly higher than non-toxic M. aeruginosa FACHB-469 after both strains had been grown at temperatures ranged from 20 to 35 ℃ for 10 days. The maximal photochemical efficiency (F_v/F_m) of both strains decreased significantly when they were exposed to stressful irradiance (600 mumol·photons·m~(-2)·s~(-1)) for 4 h, however, the F_v/F_m of toxic M. aeruginosa FACHB-905 was significantly higher than that of non-toxic M. aeruginosa FACHB-469 at 30 and 35 ℃. In brief, the toxic M. aeruginosa FACHB-905 showed higher potentialities of growth, photosynthetic capacity and resistance to stressful irradiance compared with non-toxic M. aeruginosa FACHB-469 after they had been acclimated to temperatures ranged from 20 to 35 ℃ for 10 days. The results indicated that global warming may favor the predomination of the toxic Microcystis species in natural waters, which would further aggravate the ecological risk of Microcystis blooms.