Objective：To evaluate the difference of periapical bone defect morphology caused by apical periodontitis（AP）and vertical root fracture（VRF）. Methods：Cone-beam computed tomography（CBCT）data of the maxillary and mandibular posterior teeth with AP and VRF and peripheral periapical defects were selected and reconstructed by Mimics software and quantitatively analyzed in the defect area. The percentage of bone defect volume above the level of the apical foramen of the two groups was calculated as the volume of the total bone defect. Results：The volume ratio between the two groups was statistically significant（P < 0.05）. When the volume ratio tends to 1，the possibility of vertical root fracture is great. Conclusion：VRF-induced periapical bone defect is mainly located above the level of the apical foramen of the tooth. Quantitative measurement of the periapical bone defect contributes to the diagnosis of VRF.