An allelopathic plant-filler floating bed was developed through the integration of the allelopathy of aquatic plants and conventional floating beds and by the use of biological fillers. Hydrocotyle vulgaris was chosen as the experimental plant, and gravel, maifanite, shell, activated alumina, and polyurethane were chosen as the fillers of the floating bed. The experimental results are as follows: (1)The planting water of Hydrocotyle vulgaris can effectively inhibit the growth of Microcystis aeruginosa. (2)Except for the shell, the other four fillers can significantly improve the water quality and effectively reduce the concentration of chlorophyll a. (3)The allelopathic plant-filler floating bed can effectively reduce the concentrations of COD_Mn, TN, TP, and the turbidity in eutrophic water, increase the dissolved oxygen in the water, and remove the odor.