【Abstract】 Objective To approach the feasibility of FlaB?PCR used for the detection of leptospira. Methods The proper  primer  was  synthesized  according  to  FlaB  gene and its sensitivity and specificity was evaluated compared to the primer G1/G2 recommended by public health industry standard. It was applied to leptospira detection of frog and rats which were from Longyou and Changshan. And it was identified by PCR. Results FlaB?PCR was highly sensitive and specific, and pathogenic leptospira DNA could be specifically amplified with the selected primer. The PCR results on leptospira isolated from Zhejiang province  in  2007 were in accordance with the serology results. The positive rate of the kidneys of rats and frogs was 20.94% by FlaB?PCR. Compared with the primer G1/G2 recommended by public health industry, the coincidence of two methods was 90.54%. Conclusion FlaB?PCR can detect the pathogenicity leptospira specifically and quickly, which can reflect the carrying rate of leptospira in wild animals accurately and efficiently and provide the evidence for leptospira control.