In order to understand the purification processes of bacteria communities in reclaimed water replenishment constructed wetlands, this study employed 16S rDNA clone library technique to analyze the community diversity of endophytic bacteria in roots of typha, which growed in Baihe constructed wetland in Miyun. We further investigated the relationship between endophytic bacteria communities and water quality factors. The results of 16S rDNA clone library showed that community included four major groups: the most dominant phylum was Proteobacteria (92.85%), including Gammaproteobacteria (63.04%), Betaproteobacteria (26.09%), Epsilonproteobacteria (2.48%) and Alphaproteobacteria (1.24%); The second group was Firmicutes (1.24%); the third phylum was Verrucomicrobia (0.62%); the fourth phylum was Bacteroidetes (0.31%). Additionally, 4.65% bacteria was unclassified. Stepwise discriminant analysis suggested that endophytic bacteria in roots of typha were significantly important in the geochemical cycle in reclaimed water replenishment wetlands. Specificially, 41.60% clones involved in the nitrogen cycle in wetlands, 12.42% clones involved in the phosphorus cycle in wetland, 14.92% of clones involved in the carbon cycle in wetland, 26.08% of clones involved in the metabolism of organic matter, 11.8% of the clones absorption of heavy metal matter. Thus, endophytic bacteria in plants may play a major role in the process of removal of nitrogen, nitrification and denitrification except for phosphorus removal. As our results concluded through single sampling, more evidences should be abtained by multi temporal sampling.