[Objective] The aim of this study is to evaluate the feasibility of using purified recombinant OMP28 to diagnose Brucella-infected sheep and goats. [Methods] We expressed and purified recombinant Brucella OMP28 protein in Escherichia coli system as a diagnostic antigen in an I-ELISA. Four different Brucella species (B. melitensis 16M, B. melitensis M28, B. abortus 2308, and B. suis S1330) were used to inoculate sheep and goat and sera samples were collected every two weeks, till 42 weeks post-inoculation. The antibodies against LPS and OMP28 were parallel compared by LPS-based and OMP28-based I-ELISA respectively. [Results] All Brucella-infected individuals could produce high levels of antibodies against LPS, but only B. melitensis 16M- and B. melitensis M28-infected sheep and B. melitensis 16M- and B. abortus 2308-infected goats could produce antibodies against OMP28 and the OMP28 specific antibody were undetectable in the rest groups. [Conclusion] OMP28-based I-ELISA showed specificity for both Brucella species and host kinds, which obviously limited its reliability as an antigen for diagnosing brucellosis in sheep and goats.