Abstract: Objective To evaluate the effect of Vaseline lip smear in the treatment of patients with root canal treatment. Me thods We selected 60 patients who needed root canal treatment, and according to the randomized method, we randomly divided them into two groups: observation group and control group. The observation group used Vaseline lip smear, the control group was given Erythromycin Ointment coated lips. The clinical effect after root canal treatment were compared between two groups. Re s ults There was no cases of altercation ulcer or tear in the observation group after the root canal treatment, and 1 case of angular ulcer was found in the control group.Comparison between groups, the difference was not statistically significant, that of Vaseline and Erythromycin Ointment in preventing mouth ulcer or tear, no statistically significant differences between groups P>0.05. In the taste evaluation, there were 26 cases feeling good taste in the observation group, accounting for 86.67% , and 12 cases feeling good taste in the control group, accounting for 40% . There was statistically significant difference between two groups (P <0.05) . Conclus ion After the root canal treatment, the use of Vaseline can prevent chapped lips, ulcers, the effect is equivalent to Erythromycin Ointment, but in terms of taste, the patient more likely prefer Vaseline for lip moisturizer.