This study focuses on the analysis of algae growth when nitrogen is enough and phosphorus is different though the method of enclosure experiments. and to determine the influence of phosphorus for algae population structure. The results showed that the optimum value for algae grew isρp=0.14mg·L-1in the different phosphorus concentrations, and algae grew better at phosphorus concentration more than 0.14mg·L-1than less than it. Community structure of phytoplankton has a little change between the experiments.The dominance of diatom is much larger than that of other phylum.The phosphorus can influence algae growth but has little effect on phytoplankton succession.A further research about the reason of phytoplankton succession in Xiangxi bay is needed.