Abstract: Fe was suspected as a limitingfactor controlling phytoplankton abundance in certain areas of the open ocean1Some experiments have been run to examine growth limitation of oceanic and coastal species as a function of Fe3+concentrations.Few studies are conducted corresponding the effect of Fe3 +concentrations on algae in lake.Oscillatoria planctonica Woloszynska,a bloom-forming cyanobacterium,was grown in Fe-deficient and Fe-replete batch cultures using ambient levels of physical factors in natural blooms and in BG11 media1The characteristics of growth,biochemical composition and photosynthesis of Oscillatoria planctonica under Fe3+concentrations between 0-30 mmol/L were covered in this paper.The results showed that the growth and biochemical composition(chlorophyll a and protein contents)were limited when Fe3 +was below10 nmol/L and were alleviated by the addition of Fe3+.When the Fe3+concentration reached 10 mmol/L,the final yields and specific growth rate were 3 and 4 times respectively compared with those under zero added Fe3+condition1Chlorophyll aspecific light-saturated photosynthetic rate(Pm),dark respiration rate(Rd) and apparent photosynthetic efficiency(α) under Fe-replete conditions were significantly higher than those under Fe-limited conditions,whereas light saturated point(Ik)and light compensatory point(Ic) showed the contrary.It is evident that Fe deficiency imposed a restriction on the growth and division of Oscillatoria planctonica cells