Abstract: To quickly detect the specific antibody levels in serum of chickens which infected by Eimeria tenlla, EtMIC4-N protein was expressed and purified by Escherichia coli. The reactogenicity of EtMIC4-N protein was identified by Western Bloting. A BAS-ELISA method was established using EtMIC4-N protein as the coating antigen and biotin conjugated goat anti-chicken IgG antibody as the second antibody, streptavidin peroxidase conjugated as the enzyme-labeled antibody. The results indicated that the best concentration of coating antigen was 7 μg/mL, the best blocking buffer was 1% BSA, the best dilution of sera samples, the second antibody, the enzyme-labeled antibody was 1:80, 1:100000, 1:100000 respectively, the best chromogenic reaction time was 15 min, and coefficients of variation in intra-batch and inter-batch were less than 10%. The animal experiment results suggested that BAS-ELISA, which was simple, rapid, sensitive and low-cost, could be used to detect the antibodies against chicken Eimeria tenlla.