Abstract: Objective：To determine whether there is significant difference in of rpl gene of fluoride-resistant Streptococcus mutans cultivated in fluorine-containing medium. Methods：Fluoride-resistant Streptococcus mutans were subcultured in BHI containing 1g/L NaF or without NaF, and its parental strain was subcultured in BHI without NaF. After 11h (logarithmic phase) or 20h (platform stage) cultivation, total RNA of the three groups were extracted and reverse transcribed，and the impression level of rpl were detected by qRT-PCR. Results：The of rpl gene of fluoride-resistant Streptococcus mutans cultivated in fluorine-containing medium, compared with fluoride-free medium, had no significant difference in the logarithmic phase (P＞0.05), but increased in the platform stage (P<0.001). Compared with its parental strain, the of rpl gene of fluoride-resistant Streptococcus mutans, whether cultivated in fluorine-containing or fluorine-free medium, was significantly decreased (P<0.001). Conclusions：The presence of fluoride could weaken the decrease of the of rpl gene in fluoride-resistant Streptococcus mutans, compared with its parental strain, in the platform stage, but had no influence in the logarithmic phase.