Ferrum is one of the important nutrient sources for algae in lakes. The changes of concentration in water body have great effect on the formation of dominant algae. Microcystis aeruginosa, Scenedesmus quadricauda and Cyclotella were examined in M11 culture medium which included different Fe2+ and Fe3+ concentration. Growth curves of these three algae were fitted by logistic growth-model, respectively. The maximum biomass K, inflection t and growth rate µ of those algae were investigated. The effects of Fe2+ and Fe3+ on the growth of algae were investigated by using the Monod equation. The semi-saturation constants were calculated. The results showed that the maximum biomass of these three algae did not increase with the increasing of Fe2+ and Fe3+ concentration. Low concentration of Fe2+ (200-500 mg/L) and high concentration of Fe3+ (2000-5000 mg/L) were more suitable to the growth of three algae. The sequence of the maximum biomass was: Scenedesmus quadricauda>Microcystis aeruginosa>Cyclotella.