Abstract: Differences in the functiona1 diversity of microbia1 community between rhizosphere sediment of Acorus calamus and non-rhizosphere sediment were investigated using Biolog-Eco microplates. Results showed that the growth of Acorus calamus could significantly increase the microbial activity and diversity in the rhizosphere sediment. The total microorganism activity (AWCD, average well color development) and the diversity including the Shannon-Wiener index, Simpson index, richness index and Pielou evenness index of rhizosphere sediment was significantly higher than that of non-rhizosphere sediment. Microorganisms using sugar as the main carbon source was the main microorganism groups in the rhizosphere sediment of Acorus calamus, whereas microbes in the non-rhizosphere sediment mainly used ester and amine as carbon source. The carbon sources causing the metabolic differences between non-rhizosphere sediment and rhizosphere sediment were D-Cellobiose, ?-Methyl-D-Glucoside, Glucose-1-Phosphate, D-Galacturonic Acid, D-Glucosaminic Acid, Phenylethyl-amine, N-Acetyl-D-Glucosamine, D-Galactonic Acid y-Lactone, D-Mannitol and D,L-a-Glycerol. Analysis on the differences of functional diversity in microbial community between rhizosphere and nonrhizosphere sediment aims to reveal the mechanism of rhizosphere effect of aquatic macrophyte and provides scientific basis for improving the efficiency of pollutant removal by aquatic macrophyte.