Based on the data of some Chinese lakes，the relationship between biomass, distribution and dominant species of aquatic macrophytes and phytoplankton biomass, chlorophyll a, water transparency and trophic status of lakes is presented in the viewpoint of lake eutrophication. It is shown that the growth of these two primary producers in shallow lakes is ncgativclly correlated, which is reflected in the water quality indexes and lake trophic status. The role of light limitation, nutrient supply and biochemical inhibition in the interactions between aquatic macrophytes and phytoplankton is discussed briefly.