The invention discloses a brucellosis specific fusion protein antigen. The brucellosis specific fusion protein antigen is a fusion protein expressed by Escherichia coli BL21 (DE3) after inserting a fusion protein gene constructed by serially connecting amino acid sequences on dominant antigen epitopes of Brucella outer membrane proteins BP26, OMP31, OMP16 and OMP2b to pET-28b, approaches a natural protein in conformation, keeps the antigenicity and the solubility of the natural protein, and can be used as a diagnosis antigen to produce a human brucellosis antibody ELISAS kit. The kit overcomes the disadvantages of long separate culture enrichment time, easy pollution to environment and easy human infection of traditional etiological diagnosis, and also improves the severe cross reaction of traditional immunological methods. The kit has the advantages of strong specificity, good repeatability and high sensitivity, provides means for rapid, accurate and specific diagnosis of brucellosis, and provides bases for early diagnosis and early treatment of brucellosis patients.