Objective To evaluate the clinical efficacy of Ⅰ root BP plus apical barrier technique in the treatment of periapical periodontitis of permanent teeth with open apical foramen. Methods From March 2020 to March 2021, 40 patients with periapical periodontitis of permanent teeth with open apical foramen in our hospital were selected as the research objects, and they were randomly divided into control group and experimental group, with 20 patients in each group. The control group was treated with MTA root tip barrier, and the experimental group was treated with Ⅰ root BP plus apical barrier technique. The operation time, clinical efficacy and adverse reactions were compared between the two groups. Results The operation time of the experimental group was (6.56±1.23) min, which was shorter than (10.23±1.45) min of the control group, and the difference was statistically significant (P0.05). The incidence of adverse reactions in the experimental group was 5.00%, which was lower than 10.00% in the control group, but the difference was not statistically significant (P>0.05). Conclusion Both Ⅰ root BP plus and MTA are apical sealers for apical barrier technique, while there is no significant difference in clinical efficacy and safety between the two, but Ⅰ root BP plus has better performance and can shorten the treatment time.