The bacterial communities of activated sludge from nine wastewater treatment plants (WWTPs) located in three cities in China were examined using high-throughput MiSeq sequencing. The results showed that there were 57 genera of bacterial populations commonly shared by all nine systems, including Ferruginibacter, Dechloromonas, Zoogloea, Gp4, Gp6, etc., indicating that there was a core microbial community in the microbial populations of WWTPs at different geographic locations. Canonical correspondence analysis (CCA) results indicated that the bacterial community variance correlated most strongly with water temperature, dissolved oxygen (DO), concentrations of chemical oxygen demand (COD), and solids retention time (SRT). Variance partitioning analyses suggested that wastewater characteristics had the greatest contribution to the bacterial community variance, explaining 21% of the variance of bacterial communities independently, followed by operational parameters (17%), and geographic location (11%). This study provided insights into the diversity and bacterial community structures in geographically distributed WWTPs.