Objective: Dental caries seriously affect people's physical and mental health， especially since the incidence of children is increasing year by year. Dental caries is one of the oral diseases that people pay more attention to at present. Many studies have shown that Streptococcus mutans is a key pathogen for the formation of dental caries. Screening lactic acid bacteria strains with antibacterial activity against Streptococcus mutans provides a new direction for preventing and treating dental caries. Methods: The strains were screened from traditional fermented foods in Guizhou， and their antibacterial effects were studied. The acid and bile salt tolerance of the strains were analyzed. The selected strains were subjected to 16s rDNA sequence homology analysis to identify their species. Results: Ten strains of lactic acid bacteria had antibacterial activity against Streptococcus mutans， among which MJ01 had the strongest antibacterial activity. After rescreening， compared with LGG， the antibacterial activity of MJ01， MJ02， SCZ01， SCZ03 and PC01 against Streptococcus mutans was significantly stronger than that of LGG. MJ01 (survival rate 93.40%) and SCZ01 (survival rate 97.74%) had strong acid resistance. MJ01 (survival rate 87.00%)， MJ02 (survival rate 93.18%)， and SCZ03 (survival rate 82.71%) had strong bile salt tolerance. After identification， 6 strains (SCZ02， SCZ01， KLST01， PC01， KLST02， MJ03) were identified as Lactobacillus plantarum， MJ02 was Lactobacillus pentosus， SCZ03 was Lactobacillus Argentina， ZLJ01 was Lactobacillus plantarum， MJ01 was Lactobacillus brevis. Conclusion: Four strains (MJ01， MJ02， SCZ01 and SCZ03) with strong antibacterial activity were screened， which provided a theoretical basis for further development and utilization of functional foods or microecological preparations.