Chlorella pyrenoidosa (Chlorophyceae) is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity ofC.pyrenoidosa cultures.In this study,we investigated effect of high temperature (35,38,or 41℃) on the balance between photosynthetic light absorption and energy utilization of C.pyrenoidosa.In contrast to 30℃,higher temperature of 35 or 38℃ did not inhibit the growth of C.pyrenoidosa.Treatment in 35℃ maintained the balance.Moreover,the PSI acceptor side in 38℃ was over-reduced and PSII reaction centers were over-excited under strong light,which destroyed the balance and generated active oxygen species (AOS).However,the activated antioxidant enzymes might remove completely the over-production of AOS,thereby protect C.pyrenoidosa cells from photodamage.It shows that this C.pyrenoidosa strain could tolerate as high as 38℃.Furthermore,treatment in 41 ℃ resulted in more lack of the balance than that in 38℃.However,the activities of antioxidant enzymes stopped increasing in 41℃,and were not strong enough to remove the excess AOS.Therefore,treatment in 41℃ could decrease the growth ofC.pyrenoidosa.In addition,strong and longtime light exposure would cause serious photodamage to C.pyrenoidosa cells.