Abstract: After fellowing up 39months of a randomized controlled field trial of type I inactivated vaccine against HFRS in Jiande county,401 persons blooded w ere before and after 39 month of vacxination IFA and M CPENT w ere used in testing the titer of IgG and neixtralizing antibody in sera respectively;Epidemiology effect of type I inactivated vacx;ine against HFRS was studied too. In 369 persons of negative IFA antibody before vaccine givers positive serocxmversion rate and gecxnetric mean titers(GMT)of IFA antibody w ere 15.99% and 1.66 after 39months of vacCine inocuhted respectively also poshive seroc;onversion rate and GMT of MOPENT antihody were 7.32% and 1.66 respectively; Protection efficary of vacxine was 100% and type I inactivated vaccine against HFRS could protect typell case of HFRS. The middle-tem of epidamiolgy effect of typel inactivated vaccine against HFRS was better and antibody level of vaccine induced after 39 months decreasedmore Antihody reaction of initial and boost vaccine receiveed after 2-3week should bem ain variables of evaha tion inmunogenicity of vaccine.