This study was conducted to investigate the similarity between hemagglutination inhibition (HI) test and enzyme-linked immunosorbent assay(ELISA), the HI titer and mean ratio S/P ratio) of avian influenza virus. To perform this study, the 1,457 sera of layers 21 farms in May, July and September, respectively. As a result of HI test, positive rates were 480 to 422 (92.1%) in May, 494 to 394(79.8%) in July and 483 to 402(83.2%) in September, and the mean antibody titer were 4.6, 4.3, 4.0 to 0.3 decreased, respectively. The positive rates by ELISA, 480 to 475(99.0%) in May, 494 to 485(98.2%) in July, 483 to 472(97.7%) in September, and the mean S/P ratio were 2.319, 2.557 and 2.380, respectively. The result of HI test and ELISA positive 480 to 422(92.1%), 475(99.0%), 494 to 394(79.8%), 485(98.2%) and 483 to 402(83.2%), 472(97.7%). Therefore, ELISA was shown more sensitive compare the HI titers.