Abstract: DNA extracted from Brucella （Rough、Smooth） and five non-Brucella micro-organisms were amplified by PCR using 2 pairs of primers specific for the genes encoding a 31-kDa Brucclla protein. Two DNA fragment of the expected size （591 bp and 460 bp） were amplified from Brucella （R、S） and one DNA fragment of the expected size （460 bp ） was amplified from Brucella using NT-PCR ,but no band was observed in five non-Brucella micro-organisms. The sensitivhy of the reaction was determined with different concentrations of genomic Brucella （R、S） DNA. As few as 1 pg DNA could be detected by this method.