Abstract: The abundance, composition, predominant species and community diversity of bacteria were invesngated in five oxidation ponds in Wuhan. The bacteria from the oxidation ponds belong to 12 genera, namely, Pseudomonas, Corynebacterium, Achromobacter, Microbacterium, Bacillus, Chromobacterium, Brevibacterium, Staphylococcus, Micrococcus, Flavobacterium, Escherichia and Streptococcus. Bacteria abundance, composition and diversity index were different in different oxidation ponds and were related to the extent of pollution. The diversity index can therefore be used to monitor the efficiency of purification in oxidation ponds.