Abstract: Paper machines offer a suitable environment for microbial growth, which results in slime problems during the process of papermaking. Investigation of the bacterial diversity in whitewater which recycled in paper mill UPM was carried out in this paper. Total DNA were directly extracted from the whitewater sample. 16S rDNA were amplified directly from purified DNA by PCR with universally bacteria-specific rDNA primers and cloned. Sixty-one bacteria were identified by partial sequencing of their 16S rDNAs. Twenty-eight operational taxonomic units(OTUs)were clustered in the following phyla including Proteobacteria(77.05%), Firmicutes(11.48%), Actinobacteria(4.92%), Deinococcus-Thermus(3.28%), Bacteroidetes(1.64%),Cyanobacteria(1.64%). Bacterial diversity was high in the whitewater sample. The results showed a high proportion of Schlegelella aquatica in the white water samples. It was the first time that Schlegelella aquatica strain had been identified from a paper machine in China. We also identified the red-slime formation bacteria Deinococcus-Thermus in whitewater sample.