Abstract: Cattail aquaculture systems with three different root coverages (shading rates) of 50%, 70% and 90% were constructed by root induced amplification, and the COD_Cr removal capacity and bacteria diversity on root surface of the cattail roots were investigated. The results showed that the root volumes were 1.74, 3.48 and 4.30 L/m², which corresponded to the 50%, 70% and 90% root coverage systems, respectively. Moreover, the three systems all performed effectively in removing organic compounds in artificial sewage, with COD_Cr removal rates of 8.28, 8.78 and 13.46 g/(m²·d) in the 50%, 70% and 90% root coverage systems, respectively. This indicated that organic removal capacity could be enhanced by increasing the root volume or adding fiber packing. In addition, the analysis of ⅡluminaMiseq PE sequencing data found that the diversity and composition of bacteria on the root surface and packing surface significantly differed among the three different systems. Though the dominated bacteria in phylum level were similar, among which Proteobacteria and Firmicutes were the most abundant phylum, the richness of bacteria in the root samples was lower than that in the packing samples. The constitution of dominate bacteria (OTUs) on the root surface was quite simple, which was composed by 1-3 top abundant OTUs with relative abundance over 10%. Furthermore, the types of dominate species differed between samples from root and parking. Enterobacter, Acinetobacter and Clostridium were dominate genera in root samples, in which OTUs2, OTUs4 and OTUs8 were representative sequencing with 100% similarity to Enterobacter ludwigii, Acinetobacter soli and Clostridium diolis, respectively. By contrast, Bacillus and Pseudomonas were dominant genera in packing samples, in which OTUs3 and OTUs11 were representative sequencing with fairly high similarity to Bacillus funiculus NAF001 and Pseudomonas argentinensis.