The Streptococcus mutans were selected for experiment. The minimum inhibitory concentration （MIC） and minimum bactericidal concentration （MBC） of cinnamaldehyde were determined by the micro broth dilution method. Cinnamaldehyde was added to the commercial adhesive Single Bond 2（SB2） in the mass fractions of 2%， 4%， 6%， and 8% to prepare the antibacterial adhesive. The commercial adhesive SB2 was used as control groups； the specimens were prepared and they were co-cultured with the bacteria. The plate colony counting method was used to determine the number of bacteria attached to the surface of the specimens and the antibacterial rates were calculated； the bacteria attached to the surface of the specimens were subjected to live/dead bacterial staining experiments to observe the state of bacteria attached to the surface of the specimens. The adhesive was incubated with the cell culture solution for 24 h to prepare the extract. The MTT method was used to determine the in vitro cytotoxicity of the adhesive and its cytotoxicity level was evaluated. On this basis， an experimental group with significant antibacterial properties was selected， and the micro-tensile test was used to measure the micro-tensile strength of the adhesive and evaluate its immediate adhesive performance.

The MIC and MBC of cinnamaldehyde were both 250 mg·L^－1， and cinnamaldehyde had a good antibacterial effect； when the mass fractions of cinnamaldehyde were 4%， 6% and 8%， the antibacterial rates of the adhesive were all higher than 99%. In the in vitro cytotoxicity experiment， under the same dilution ratio， compared with control group， the cytotoxicity level of the antimicrobial adhesive did not change significantly. According to the results of the antibacterial experiment， 4%， 6%， and 8% cinnamaldehyde groups were selected for the micro-tensile experiment. Compared with control group，the micro-tensile strengths in 4%，6% and 8% cinnamaldehyde groups had no statistically significant differences（P>0.05）.

Cinnamaldehyde has good antibacterial properties； when the mass fraction of cinnamaldehyde in the commercial adhesive SB2 is higher than 4%， the antibacterial adhesive has significant antibacterial properties， and its in vitro cytotoxicity and immediate bonding properties are not affected.