In this paper, a method of automatic surgical planning for mandibular osteotomy based on automatic identification of mandibular landmark points was proposed with facial skeletal contour surgery. A mandibular osteotomy plane optimization model was established, allowing key anatomical measurement parameters to be obtained. The analysis of the preoperative CT images of 100 patients with mandibular osteotomy showed that the average RMS error of the automatic identification algorithm was 1.87 ± 0.33 mm. To verify the effectiveness of the mandibular angle osteotomy surgical planning system on real cases, three clinical trials were conducted, and the results of the surgical planning scheme could meet the clinical needs.