Objective To illustrate the volume changes of mandibular outer cortex after been grafted to different recipient sites of facies cranii. Methods Six cases underwent onlay bone graft to the angle and body part of mandible and malar surface simultaneously by using mandibular outer cortex. Three dimensional computed tomography （3D-CT） datum of immediate postoperative and 6 months postoperative of each case were collected systematically. By true-up and dissection techniques based on 3D-CT, volume changes of bone graft at different recipient sites were observed and analyzed 6 months postoperative. Results 6 months after onlay bone grafted, bone resorption occurred. To different recipient sites, bone resorption rate was unequal. At the mandible area, bone resorption rate was 20.8%± 7.2%, the main site of resorption was at the lower and posterior border of mandible. At the anterior part of maxilla, bone resorption rate was 11.2%±2.3%. Statistics showed significant difference of resorption rate between the two sites （P
