Objective: To investigate the inhibitory effect of honeysuckle on Streptococcus mutans UA159 in vitro. Methods: We used a double-dilution method to measure the minimum inhibitory concentration (MIC) of honeysuckle against Streptococcus mutans UA159. Lonicerae lonicerae powder was dissolved in the solvent DMSO, different concentrations of liquid medicine were prepared, and bacterial liquid was added. The solution control group and bacterial liquid control group were set at the same time. The growth and acid production of UA159 were determined using antibacterial experiments. A growth curve and acid production curves were drawn, and the adhesion rate and adhesion inhibition rate were calculated. The effect of honeysuckle on the formation of Streptococcus mutans UA159 was determined by crystal violet quantification, and a microscope and a scanning electron microscope were used to observe biofilm formation and structural changes. Results : The MIC of honeysuckle against Streptococcus mutans UA159 was 12.5 mg/mL. The bacteriostatic experiments showed a difference in the growth, acid production and adhesion of UA159 after honeysuckle treatment (P<0.05) compared with the controls, and the inhibitory effect increased as the drug liquid concentration increased. Crystal violet quantification showed a significant difference in biofilm formation between the pharmaceutical liquid group and the control group (P<0.05). Meanwhile, the forward microscope showed a significant decrease in biofilm formation. Under SEM, the number of bacteria decreased significantly at 0, 6 and 12 h after honeysuckle addition. Conclusion Honeysuckle inhibits the growth and acid production of UA159 and inhibits adhesion and the formation of biofilms.