Abstract: Objective: To measure the distance of mandibular canal to the lower edge of mandible and tooth root to the alveolar crest.Methods:The panoramic tooth slice of 100 heathy 18 to 40 years old humans without periodontal disease were detected,and which were divided into man and woman group.The distance of tube edge,tube root and tube crest of all people were measured.Results:The distance of tube edge,tube root and tube crest were 5 to 12 cm,1.5 to 10 cm and 14.5 to 23 cm,respectively.The root tip point ligature of tooth 5,6 and 7 was circular arc line with the center of nasal bone root.The mandible lower edge and alveolar ridge top ligature were concentric relationship with the center of nasal bone root.There were not significant differences between man and woman group(P 0.05).Conclusions:According to the two-dimensional position characteristics of the mandible,the vertical position characteristics are feasible,it can provide a theoretical basis for mandibular fracture rigid internal fixation,tooth extraction,root canal treatment.