Abstract: In this study, an indirect Enzyme-Linked Immunosorbent Assay (ELISA) method for measuring antibodies to Classical Swine Fever Virus (CSFV) was established using recombinant E2 proteins of CSFV C and LT strains, respectively. The optimum dilutions of the E2 antigens and serum were 1:160 and 1:320, respectively. Coating concentration of the E2 antigen was 11.7 �g mL 1; the optimal concentration of enzyme-labeled antibody was 1:800; the optimal reaction times of the first antibody and secondary antibody were 1 h and 45 min, respectively. The tests showed that the E2 antigens were not reacted with both anti-BVD antibody and antibodies against other pathogens which are able to induce abortion of pregnant pigs and death of young piglets. A critical value of the method was 0.3503, namely OD of the tested serum 0.35, it was positive for CSF; <0.35, it was negative for CSF. It was found that serum specimens from CSFV LT field strain affected pigs with being diluted to 1:1280 or more could be distinguished by the method, which showed positive in LT strain-E2 ELISA but negative in C strain-E2 ELISA.