Abstract: Intends to use the pre- screened lactic acid bacterias that can inhibit Streptococcus mutans,oral application characteristics of lactic acid bacteria that inhibiting Streptococcus mutans were studied.The study measured lysozyme,antibiotic,salts and acid tolerance of L. plantarums,measured the auto- aggregation ability and co- aggregation ability of five lactic acid bacteria( Lactobacillus plantarum,L.plantarum) K25,SKT109,YW3-2,YW5-1 and YW1-1 with S.mutans.And the infuence of L.plantarum on auto- aggregation and exopolysaccharide synthesis of Streptococcus mutans was determined. The results showed that five lactic acid bacteria have a certain tolerance for lysozyme,much higher than the concentration of lysozyme in human saliva( 1~57 μg / m L).Five lactic acid bacteria also had a certain tolerance for salts and acid.L.plantarum YW5-1 showed the best tolerance to antibiotics.Adding supernatant of L.plantarum K25,YW5-1 and YW1-1 could reduce the ability of S.mutans to synthesizing exopolysaccharide.The auto- aggregation ability and co- aggregation of YW5- 1 and K25 were best of the five Lactobacillus plantarum( L.plantarum),and after adding lactic acid bacteria,auto- aggregation ability of S. mutans could be reduced.