According to the high conservative region of 16S rRNA gene in bacteria, PCR primers of the broad-range bacteria, gram-positive bacteria and gram-negative bacteria were synthesized to detect 13 bacterium species and (40) clinical specimens. All the tested bacterium species were positive. The lowest concentration of Escherichia Coli detected by serial dilution was 4 CFU.ml-1. The positive rate of PCR (27/40) was higher than that of bacterium culture(18/40). The results indicate that these PCR primers possess high specificity and sensitivity in identifying 16S rRNA gene of bacteria.