Objective To detect the homologous bacteria or mutant strains of Yersinia pestis bubonic plague during the resting period of plague. Methods Meriones unguiculatus were captured by clamping method and Citellus dauricus were captured by bow clamp method in Kangbao rangeland monitoring station of the plague natural foci of Hebei province during May to June in 2016. The intestine and the tip of the tongue were sampled, and Jerson 's bacteria were isolated. Morphological and biochemical identification and PCR identification were carried out. Results In total 93 of 363 samples were found positive for strains of Y. pestis of TSI. But PCR did not validate it. Conclusion There were closely related bacteria to Y. pestis in the natural foci of plague. Further identification of three sugar iron positive strains is needed.