Eradication program of brucellosis is depending mainly on the detection of animal reactor by different brucella serodiagnosis tests. The usefulness of diagnostic tests depends on the accuracy of test result, which in turn depends on specificity and sensitivity of the test. The standard serological tests such as Rose Bengal Plate Test (RBPT), Buffer Acidified Plate Test (BAPT),and Tube Agglutination Test (TAT) are routinely used for the accurate diagnosis of brucellosis.So in this study it was prepared proposed to establish the comparative analysis of the efficacy of adding preservatives such as phenol (0.35%), thimerosal (0.01%), and formaldehyde, (0.5%) on the morphological characters, reactivity performance and microbiological analysis of brucella antigen in order to turn out contamination to keep its efficacy along the shelf life time of them. After adding the preservatives to antigens, every antigen has been evaluated for the physical inspection, pH, auto agglutination, morphological characteristics, microbiological analysis and the sensitivity testes with positive and negative sera. These parameters were equal in all antigens with no regard to the preservative used. The best morphological profile with appropriate antigenic stability at 4°C has been noticed in formaldehyde preservative. So, it could be recommend using 0.5% formaldehyde as a preservative for antigens especially it is the most cost effective one for a long period of conservation