Objective: Streptococcus mutans is recognized as a primary etiological agent of dental caries.It was found that topical application of farnesol could affect the virulence of S.mutans biofilms,Until now few studies have been conducted to evaluate the morphological changes of S.mutans biofilms exposed to farnesol and little is known about the molecular mechanism of S.mutans exposed to farnesol.This study aimed to evaluate the effects of farnesol on Streptococcus mutans biofilm formation and explore its molecular mechanism.