Objective:To measure the mesio-distal interradicular space of posterior teeth at different height by CBCT.Methods:60 subjects with skeletal Class Ⅰ,Ⅱ and Ⅲ patterns were included(n =20).From the distal of first premolar to the mesial of second molar,the mesiodistal width at the height of 2,4,6,8 and 10 mm from the alveolar crest were measured and analysed.Results:The interradicular distance was larger than 3 mm within 4-10 mm height in maxilla and in mandible.The maxillary mesiodistal width values measured between the first premolar and second premolar in skeletal Class Ⅰ and Class Ⅱ pattern was greater than that in Class Ⅲ(P ＜0.05) and there was no significant difference in other zones.In the mandible,the values of skeletal Class Ⅲ pattern were greater than those of skeletal Class Ⅰ and Class Ⅱ pattern(P ＜0.05).Conclusion:The suitable interradicular zone is within 4-8 mm to the alveolar crest between the second premolar and first molar for miniscrew implant placement in maxilla,and over 4 mm between the first molar and second molar in mandible.The difference of interradicular spaces in sagittal skeletal features is existed.