Abstract: To evaluate and compare the antibacterial activity of conjugated linoleic acid producing Lactobacillus(CLA-producing Lactobacillus) to E.coli,Staphylococcus aureus and Salmonella in vivo and vitro. In vitro test results showed : the antibacterial activity of LAB against E. coli was better than Staphylococcus aureus and Salmonella. The Lactobacillus showed high temperature stability up to 90℃,stability in the rage of pH2.0~5.0and anti-protease activity and anti-catalyase activity. In vivo,the Lactobacillus had more powerful bacteriostatic effect and enhanced bacteriostatic effect to be with increasing does. Conclusions : The CLA- producing Lactobacillus was proved to be of bacteriostatic actions in vitro and in vivo.