Abstract: ObjectiveTo investigate the species and quantity of host animals and vector fleas in Yulong plague focus of Yunnan province, and explore the nature of the plague focus for providing scientific bases for the prevention and treatment of plague. MethodsNine surveillant sites were selected to trap the small mammals in Yulong county district of Lijiang city from February to December in 2007. Small mammals were captured by traps inside house and by cages in the field, fleas were obtained from the small mammals trapped. The species of all small mammals and fleas were identified morphologically. ResultsA total of 2390 small mammals (rodent) were captured which belonged to 19 species of 11 genera of 5 families of 3 orders, including IEothenmys/I spp. (47.28%) and IApodemus chevrieri/I ( 37.11%). Further identification of IEothenmys/I spp by skull morphology revealed that IE. miletus, E. proditor/I and IE. melanogaster/I accounted for 19.09%, 79.25% and 79.25%, respectively，with IE. proditor/I predominating in Luzi village and Yulong mountains while IE. miletus/I predominating in remaining surveillance spots. A totoal of 625 fleas were caught from host rodents, which belonged to 6 species of 6 genera in 2 families, the majority were ICtenophthalmus quadratus/I (62.08%) and INeopsylla specialis/I (22.56%). In addition, IFrontopsylla spadix/I and ILeptopsylla/I segnis accounted for 8.16% and 5.28%, respectively. No IXenopsylla cheopis/I was found. ConclusionThe rodent hosts and flea vectors in Yulong plague focus were similar in species to that in Jianchuan, but with some unique characteristics.