The impacts of light intensity and nutrients on the growth and composition of phytoplankton(from Lake Taihu) were investigated after a treatment of low temperature(4℃) and light intensity(5μE/(m²·s)). Results showed that growth of algae under moderate light intensity(50μE/(m²·s)) was the best followed by high light intensity(200μE/(m²·s)) and low light intensity(5μE/(m²·s)). Green algae and diatom were detected under moderate and high light intensity, and the proportion of them increased with culturing time and light intensity, however, they were not detected under low light intensity. Meanwhile, nutrients enrichment bioassays were conducted under moderate light intensity to determine the influence of nutrient limitation on phytoplankton growth and structure during early bloom stage. The results indicated that algae grow better with addition of both nitrogen and phosphorus than phosphorus or nitrogen alone and neither successively, indicating that the growth of algae is sensitive to both nitrogen and phosphorus limitation, and is more sensitive to phosphorus in the early stage of blooms. Additionally, nutrients were also found to influence the structure of phytoplankton community in the early stage of bloom, as green algae and diatom were detected after introduction of nitrogen or/and phosphorus. These results implied that reducing light intensity and nutrients(mainly phosphorus) will reduce phytoplankton biomass and growth during early bloom stage. However, some cyanobacteria, Microcystis for example, which is low light intensity tolerance, may dominant after reduction of light intensity and nutrients. Green algae and diatom may dominate gradually with increasing the nitrogen and phosphorus concentrations to a certain extent, which provided possible options for selective controlling during early bloom.