Objective To analyze the imaging features and the diagnostic value of X-ray, CT and MRI of osteosarcoma in non-tubiform bone. Methods A total of 18 cases of osteosarcoma of non-tubiform bone proved by pathology were reviewed retrospectively. Eleven cases underwent X-ray, ten cases underwent CT and nine cases underwent MRI. Results Fifteen cases were primary osteosarcoma, three cases were secondary osteosarcoma(1 case was radiation-induced osteosarcoma, 1 case was secondary to postoperative osteochondroma, and 1 case was local cancerated into osteosarcoma from ossifying fibroma). The mean age was 43.3 years(range:19-64 years). Eleven cases were osteolytic lesions, with 5 cases were mixed and 2 cases were osteoblastic. Soft tissue extension were present in 17 cases, and osteoid tumor matrix mineralization were present in 16 cases. Conclusion Most osteosarcoma of non-tubiform bone occurred in older persons. Frequently the lesions were osteolytic in imagine. Combined imaging modalities of X-ray, CT and MRI can help to diagnose and differentiate this lesion.