The purpose of this study was to evaluate the guiding effect of computer-assisted design technique in local resection of exostosis osteochondroma (EOC) from the mandibular condyle. Eight patients diagnosed with EOC through computed tomographic scan were selected from January 2011 to March 2012. SurgiCase CMF 220.127.116.11 software was used for preoperative design. The osteotomy angle, depth, and tumor shape were measured to guide the surgery. The tumors were resected from the stalk 2 mm within the normal tissue to restore the unaffected condyle as much as possible. Postoperative computed tomographic scans showed that the tumors had been resected completely in all patients. The mean (SD) error between the design and the result was 1.82 (1.25) mm. Five patients had more than 1-year follow-up without recurrence. Computer-assisted design is a good way to help local resection of EOC. It can improve the accuracy of tumor resection and keep the unaffected condyle as much as possible for function.