1.X-ray examination Most of the cases show a mixed osteogenic and osteolytic bone destruction. When the tumor penetrates through the cortex and invades into the soft tissue, the most characteristic periosteal reaction is formed, such as the needle-like periosteal reaction which is arranged in parallel with the periosteum in a radial pattern, i.e. the angry hair punching the crown sign; or arranged to radiate outward from a point on the periosteum, i.e. the daylight radiation sign; or the Codman triangle, which is the periosteum being repeatedly lifted up by the tumor, the periosteum reacts to osteogenesis and forms the periosteal interruption. 2.Computed tomography (CT) scan can show the extent of tumor bone, soft tissue invasion and the relationship between tumor and major blood vessels more clearly, which is one of the important bases for surgical boundary setting. Enhancement scan can have more obvious enhancement of the parenchymal part of the tumor, so that the tumor can be distinguished from the necrotic area and surrounding soft tissues more clearly. Chest CT examination can detect lung metastasis and other obvious lung lesions at an early stage, and is the first choice of imaging examination for the detection of lung metastasis. 3.Magnetic resonance imaging (MRI) MRI is very sensitive to show the internal structure of the tumor. Most osteosarcomas show inhomogeneous low signal on TW1, and tumor parenchyma is generally high signal on TW2, while tumor bone, periosteal reaction and tumor cartilage calcification show low signal shadow. MRI plays an active role in observing the extent of soft tissue invasion of osteosarcoma, and is also the best method to show the extent of infiltration within the medullary cavity. In limb-preserving surgery, MRI is advantageous for the detection of intramedullary jumping lesions and is a key guide for extensive resection length localization of the tumor bone. 4. Isotope bone scan (ECT) ECT is based on local skeletal blood flow and bone salt metabolism, which are mostly evident at the early stage of the lesion, usually appearing 3-6 months earlier than X-ray, and are of special value for the early diagnosis of skeletal lesions, especially for asymptomatic metastatic bone tumors. Osteosarcoma shows radioactive concentration on ECT, and the extent of concentration is often larger than the actual lesion, which plays a certain reference role in the qualitative or localized diagnosis of osteosarcoma. It is helpful to determine whether there are other bone metastases of malignant tumors, whether there are multiple lesions and whether there are jumping foci. 5.Angiography Angiography can understand the richness of blood vessels of tumor and judge the vascular origin of tumor. The comparison of angiography before and after chemotherapy can be used as an important index to evaluate the effect of chemotherapy. It can also find out whether the blood vessels are pushed and displaced by the tumor or encircled by the tumor, so as to judge whether the blood vessels need to be removed and prepared for repair when removing the tumor.