【Abstract】 Objective To understand the situation of the reservoir hosts and vectors infected by Borrelia burgdorferi, the distribution of the reservoir hosts and the seasonal fluctuation of ticks in Miyun area.  Methods Ticks were caught with flag method, which were identified by Inverted microscope. The night trapping method was used to catch rats.  The pathogen from ticks and rodents was isolated with BSKⅡculture. The nested PCR was used to do etiological detection. The antibody of B.burgdorferi from goat serum was tested by indirect immunofluorescence. Results Ticks caught in Miyun area were all Haemaphysalis longicornis, which growth curve was obviously seasonal. The rate of ticks bearing pathogen was 10.16% after detection by nested PCR. Apodemus agrarius and Niniventer confucianus were the dominant species in the area, and the rate of rodents bearing pathogen was  4.26%.  The  positive  rate  of  goats  stocked  in  the  local  was  12.00%.  Conclusion The  specific fragment of B.burgdorferi was found in ticks and rodents, which showed that Miyun area maybe one of the epidemic focus of Lyme disease.