The purpose of this study was to understand the changes of antibodies before and after Foot)and-mouth disease (FMD) immunization in a sheep farm of Yuexi county, which provided reference for optimizing FMD immunization program in this farm. ELISA was used to dynamically monitor FMD antibodies in lambs that were not vaccinated against FMD and were vaccinated against FMD in the sheep farm of Yuexi County. The results showed that the qualified rates of A and O type FMD antibodies were 79.16% and 87.50% at 14 days of age, reduced to below 70.00% at 30 days of age, and then 37.50% and 45.83% at 60 days of age on lamb. The qualified rates of FMD A and O antibodies were 16.67% and 25.00% respectively after 7 days of vaccination, and increased to 70.83% and 75.00% at 21 days, which reached the national standard. The qualified rate of type A antibody reached a peak of 91.67% on 42 days, and type O antibody reached a peak of 91.67% on 56 days. The qualified rate of type A FMD antibody reached and maintained a peak of 91.67% at 42 days, and the qualified rate of type O FMD antibody reached the peak of 91.67% at 56 days. The result shows that maternal antibodies in lambs fell below the national standard nearly one month after birth and continued to decline. The antibody qualified rate rose to the national standard 21 days after vaccination, and reached a peak in about two months. [ABSTRACT FROM AUTHOR]