Abstract: Aim:The aim of this study was to evaluate the bond strength of iRoot SP with and without gutta-percha by different root canal obturation techniques. Methods: Forty single-canal upper incisors were collected and decoronated to obtain 12 mm root segments.The root canals were prepared by using ProTaper rotary files and allocated into 4 groups randomly（n=10）, then obturated with gutta-percha and(or) iRoot SP by cold lateral compaction, continuous wave condensation, single core, sealer-only backfill techniques respectively. All samples were sliced perpendicularly to the long axis from the apical to the coronal side on a low-speed microtome to a thickness of 1.00 mm . The bond strength of the 2、5、8 piece ，which was on behalf of the apical 1/3 segment, the middle 1/3 segment and the coronal 1/3 segment respectively ,were calculated by a universal testing machine and observe the fracture mode at the same time. The data were analyzed using SPSS 22.0 software package. Results:In the apical third, the SOB technology had the lowest bond strength,(P <0.05); in the coronal third, CWC technology showed the lowest bond strength, (P < 0.05). There were no significant difference among three segments in SOB technology group. The mainly fracture mode was interfacial fractures in CWC group while cohesive fracture and mixed fracture in other three groups.