Objective To study the particular imaging features of intramedullary osteoid osteoma and evaluate success rate of cold mode radio-frequency thermal ablation (RFTA) as the treatment of it. Methods Three patients had tibial intramedullary osteoid osteoma who underwent RFTA and forty-eight patients with cortical and subperiosteal lesions were treated by the non-cooled mode, finally compared the difference between the two groups. Results The swelling of marrow and the soft tissue around the nest, no Clear boundary, the nest is not typical, no hardening around the rim with intramedullary osteoid osteoma. The intramedullary soft tissue changes may show as a misleadingly aggressive appearance in MRI. Treated by the RFTA, all patients were pain-free and in good recovery. In the intramedullary osteoid osteoma group, no recurrences were observed during the 24-month follow-up period, but 28 patients who got cortical osteoid osteoma required a supplementary RF treatment to completely heal the lesion. Three patients had complete healing by the RFTA. Conclusion CT-guided RFTA should be the first treatment for intramedullary osteoid osteomas because of the high success rate and its reduced invasion. With cold-mode RFTA. The outcome is promising. The success indicators for treatment are the disappearance of pain and the absence of lesion in the ablation area detected by MRI.