The early skeletal relapse after surgery was much influenced by clockwise rotation of the proximal segment. The purpose of this study is to prove statistically that the removal of fixation plate at postoperative 2 weeks with active exercise of mouth opening could reposition not only both proximal and distal segment to its original position but also reduce skeletal relapse. All subject comprised 35 patients underwent mandibular setback via BSSRO in Kyunghee medical center by a surgeon. We divided the sample into two groups. In group 1, the fixation plate was maintained and that was removed at postoperative 2 weeks in group 2. Cephalometric radiograph were obtained before surgery, within a week after surgery, two months postoperatively. All radiograph were traced and analyzed by the same investigator and were serially superimposed on the reference lines, anterior and posterior cranial base structures. We measured the changes of both proximal & distal segment and performed statistical analysis used paired t -test(p<0.05). The results obtained are as follows that the proximal segment was displaced posteroinferiorly(clockwise fashion) at postsurgery in both group and repositioned toward its original position during follow-up periods, especially in group 2. And the distal segment was more displaced anteriorly in group 1 that didn't remove the fixation plate. In conclusion, the clockwise rotation of proximal segment is a significant factor reflecting early skeletal relapse. The early removal of fixation plate after BSSRO could reposition the proximal segment which displaced posteroinferiorly to physiologic position and reduce early skeletal relapse.