IgM antibody capture ELISA was called MAC- ELISA for short is a standard technique for Japanese encephalitis (JE) and dengue diagnosis, especially in the countries where dengue and JE viruses co-circulating. The sensitivity and specificity of MAC-ELISA technique are related to conjugate. In this study, determining the sensitive and specific of conjugate coded 12D11 and 4G2 were carried out to find out the suitable conjugate for MAC-ELISA to detect IgM antibody to dengue virus. The results showed that 12D11 conjugate at the dilution of 1/8000 had high sensitivity and specificity for MAC-ELISA to detect IgM to dengue virus and low cross reaction with JE virus antigen. Whereas, 4G2 conjugate at the dilution of 1/8000 has higher sensitivity and specificity for MAC-ELISA to detect IgM to JE virus and lower cross reactivity with dengue virus antigen. Based on the results, conjugate axled 12D11 is best selected to develop MAC-ELISA kit for the detection of IgM antibody to dengue virus in further study.