Osteoblastoma is an uncommon lesion of bone that occurred in jaw bone. The etiology of the Osteoblastoma is still undiscovered. The most frequent symptom is consistent pain which is often severe, and localized swelling and bone expansion mat occur. We experienced a case of osteo-blastoma which occurred on the lingual surface of mandibular body. It resembled tours mandibularis clinically, alveolar abscess radiologically. Biopsy was done to evaluable the tours-like bony mass. The results of excisional biopsy demonstrated an osteoblastoma. The symptoms are subsided and no signs related with recurrence have been noted. Our experience and many literatures demonstrated that Osteoblastoma must be included in differential diagnosis of bone-producing lesion.