Abstract: The community characteristics and the heterotrophic activity of heterotrophic bacteria from the root-zone (rhizosphere and root surface) of water hyacinth (Eichhornia crassipes Solms) were studied. Experimental results are as follows: (1)Twenty-four strains of bacteria were isolated from the root-zone of water hyacinth. They belong to ten genera: Aeromonas, Micrococcus, Pseudomonas Agrobacterium, Bacillus. They are the dominant genera, Chromobacterium Acinetobacter, Eschericia, Vibrio and Serratia. (2)Total bacteriaI number was in the order: rhizosphereroot surfacethe water body. (3)Heterotrophic activity was calculated from oxidation rate of glucose in bacteria. The intensity of activity was in the order: bacteria in older rootsbacteria in younger rootsbacteria in roots of withered plants, the activity was higher in bacteria in root surface than in the rhizosphere bacteria. (4)Under the conditions of 30℃ and pH 7.0, all bacteria showed high activities, but their activities were inhibited markedly at a temperature of/0℃, and a pH of 5.0 or 8.6.