The objective of this study was to determine the growth curves and antibacterial activity of two different strains of Lactobacillus salivarius. Streptococcus mutans, Porphyromonas gingivalis and Staphylococcus aureus were selected to perform antibacterial tests in vitro by the Oxford cup method. The results showed that the logarithmic growth phase of the two strains of Lactobacillus salivarius began respectively at 2 and 4 hours after inoculation and ended both at 8 hours, and the stationary phase began at 14 and 16 hours, respectively. It was proved that the bacteria cultures of both strains of Lactobacillus salivarius and their metabolites had antibacterial activity against Streptococcus mutans, Porphyromonas gingivalis and Staphylococcus aureus, and the antibacterial activity against Streptococcus mutans and Porphyromonas gingivalis was stronger than that against Staphylococcus aureus. Also, for both strains, neither bacterial sludge nor metabolite with an adjusted pH value (7.0) had antibacterial activity. Antibacterial activity of both strains of Lactobacillus salivarius came mainly from their metabolites, and it were acid or acid-dependent materials that play a key role in the antibacterial activity of metabolite.