The invention discloses an ELISA (
enzyme-linked immunosorbent 
assay) 
reagent kit for detecting IgM antibodies of 
brucellosis and application of the ELISA 
reagent kit. The ELISA 
reagent kit comprises 
brucella antigen coated microporous plates, HRP (horseradish 
peroxide) labeled 
brucella antigens, negative reference substances, positive reference substances, color developing agents A, color developing agents B, stop solution and concentrated cleaning solution. The application of the ELISA reagent kit on the basis of double-
antigen sandwich immunoassay principles includes adding to-be-detected samples into the microporous plates, binding unknown antibodies in the samples with 
solid-phase antigens, carrying out washing to form stable unknown 
antibody-
antigen complexes, adding labeled antigensinto the unknown 
antibody-antigen complexes to bind the labeled antigens with blank sites of IgM antibodies so as to form labeled antigen-
IgM antibody-antigen complexes, washing the labeled antigen-
IgM antibody-antigen complexes, and then adding the color developing agents into the labeled antigen-
IgM antibody-antigen complexes; measuring 
absorbance OD (
optical density) values under the conditionof detection wavelengths of 450 nm and then judging the to-be-detected samples according to critical values. The shade of colors and the degrees of concentration are in 
positive correlation function relationships. The ELISA reagent kit and the application have the 
advantage that the ELISA reagent kit can be used for monitoring early 
acute infection to detect the 
brucellosis of pigs, cattle and sheep.