The microbial communities of Naner block of Daqing oilfield,a moderate-temperature (44.6 ℃) and high-wax (30.7%) block,was investigated with the T-RFLP and clone library methods based on 16S rRNA gene.The results showed that the injection water (DQZ) had higher diversity than the oil produced water (DQY).The microbial communities were similar in the different oil produced water.The dominant microbes were Thauera,Hydrogenophaga,Tepidimonas,Azonexus,Azoarcus,Acinetobacter,Arcobacter Methanosaeta and Methanolinea in the DQZ,when Arcobacter,Thauera,Aquabacterium,Pseudomonas,Methanosaeta,Methanolinea and Methanoculleus were dominant species in the DQY.Thioclava,Pelobacter,Syntrophobacter,Syntrophus,Sulfuricurvum,Methanobacterium,Methanolobus and Methanococcus were only detected in the DQZ.Compared to the DQZ,Aquabacterium and Pseudomonas were specific in the DQY.The distribution of microbes corresponded to the environmental variables in the oil reservoirs such as temperature and max degree.