CT can not rule out osteosarcoma, the sensitivity of CT diagnosis of osteosarcoma is not 100%, there is a possibility of missed diagnosis. Osteosarcoma can be diagnosed according to the symptoms such as pain, mass and other symptoms combined with the imaging manifestations. x-ray is characterized by Codman’s triangle or “daylight ray” morphology, CT and magnetic resonance examination can determine the nature and scope of osteosarcoma. The sensitivity of all imaging tests is less than 100%, and false negatives may occur in the early stages of the disease or when the location of the osteosarcoma is not easily detected. The diagnostic positivity of CT for osteosarcoma is lower than the diagnostic positivity of MRI or CT combined with MRI for osteosarcoma. When a patient is suspected of having an osteosarcoma but CT is negative, further MRI may be performed. Pathologic examination by puncture biopsy or excisional biopsy is the gold standard for the diagnosis of osteosarcoma. When osteosarcoma is suspected, CT, magnetic resonance or pathology examination should be performed as prescribed by the doctor for early diagnosis and treatment to avoid delay.