Objective: To investigate the clinical and radiographic outcomes of 3 years after partial pulpotomy with iRoot BP Plus in immature permanent teeth with complex crown fracture and to provide refe-rence for the clinical application. Methods: The study was prospectively designed and 104 immature permanent teeth with complex crown fracture were randomly allocated into two groups (n=52). The experiment group received iRoot BP Plus as the pulp capping agent while the control group received calcium hydroxide as the pulp capping agent. After partial pulpotomy, all teeth were clinically and radiographically assessed at the end of 1, 3, 6, 12, 18, 24, 30, and 36 months. The success rate in the two groups was evaluated to see if there was significant difference. The root canal wall thickness in the treated teeth was compared both between the groups and within the groups with those of the corresponding healthy teeth on the opposite side, in the same patient. Results: Excluding those lost to follow-up, there were 44 teeth in calcium hydroxide group (8 teeth accounting for 15.4% were lost to follow up) and 45 teeth in iRoot BP Plus group (7 teeth accounting for 13.5% were lost to follow up) in the end. There was no intergroup difference in the success rate between calcium hydroxide group and iRoot BP Plus group (per-protocol analysis: 80% vs. 87%; intent-to-treat analysis: 67% vs. 75%). The non-inferiority margin was -10%. The 95% confidence interval of the difference in success rate was -8% to 22%. There was no significant difference in root development between the experimental teeth and contralateral control teeth. The thickness of upper 1/3 root canal in the iRoot BP Plus group was thinner than that in the CH group [(1.82±0.21) mm vs. (1.91±0.20) mm, P=0.047]. Conclusion: iRoot BP Plus used in pulpotomy can effectively preserve the living pulp and promote the development of root in the young permanent teeth with complex crown fracture.