In order to investigate the antibacterial mechanism of tea polyphenols (TPS) and theaflavins against oral cariogenic bacteria. The pH value of the culture medium, the number of bacteria adhering to the smooth glass tube wall, and the electrical conductivity value within 10 hours were measured, respectively. The effects of four concentrations of tea polyphenols and theaflavins below the MIC value were studied on acid production, adhesion, and electrical conductivity of oral cariogenic bacteria. The live/dead staining method was used to observe the effects of four concentrations of TP and theaflavins below MIC value on the biofilm activity of oral cariogenic bacteria under a laser scanning confocal microscope.With the increasing concentrations of tea polyphenols and theaflavins, the acid production and adhesion of the cariogenic bacteria gradually decreased, and the conductivity gradually increased. However, the conductivity increase was not significant (P<0.05). Compared with the control group, the 1/2MIC and 1/4MIC TP and theaflavins treatments significantly reduced the biomass of cariogenic biofilm (P<0.05). CLSM showed that the integrated optical density of green fluorescence of the cariogenic biofilm gradually decreased with the increase of drug concentration after the action of tea polyphenols and theaflavins.