【Abstract】 Objective To know the species and distributions of carnivores and small mammals in Sanjiangyuan area. Methods The investigation was done by the night trap. Results There were many carnivores and small mammals in San jiang yuan, belonging to 4 orders, 11 Familys, 27 Genera and 51 species. Conclusion Marmota himalayana, Microtus oeconomus, Mus musculus, Cricetulus longicaudatus, Ochotona curzoniae, Felis catus, Canis familiaris, Vulpes vulpes, Vulpes corsac, Canis upus,Mustela eversmanni distributed widely  in Sanjiangyuan Area. Marmota himalayana was the main host of nature plague foci in the Qinghai-Tibet plateau.

【Abstract】 This paper briefly discusses the biology and ecological characteristics of host animals and vectors infected naturally by Yersinia pestis district and the time and location of first isolation in Sanjiangyuan. It is to understand the species of animals and vectors infected and the function they plays in the plague epidemiology in order to provide the basis for the prevention and control of plague in Sanjiangyuan.