Abstract: Objective To understand and master the prevailing law of Hemorrhagic Fever with Renal Syndrome (HFRS). Methods The basis of Diagnosis of Hemorrhagic Fever with Renal Syndrome was the diagnostic standard of 《the People's Republic of China Infectious Disease Prevent and Cure Law》. The antibody of HV was determined with direct Immunofluorescent Antibody (IFAT): gather 2ml the vein blood of health person who completed the basic immunity 2 weeks, and adopt the Indirect Immunofluorescent Antibody (IFAT). Results The fluctuation range of the incidence rate was 0.49-7.40/100 000 during 1998-2002.There was a remarkable difference quality between the HFRS of local and floating population (x2=31.69,P<0.01),and appeared the spring peak and the youth(15-50)peak.The sex ratio between men and women was 1:0.26, and the rotating rate of antibody was 96.61%,Ratus norvegicus was 87.06% of the total amount and the density of it was 5.07%.The proporting of rats with virus in 2001 was the highest(6.98%).Conclusion The incidence of HFRS in Changping district showed a tendency to increase rapidly.Rattus norvegicus was the advantage species of rats.The focal point in the future should be the work of the immunity inoculating of regarding floating population as the main target.