Malignant bone tumors need to be diagnosed by combining clinical manifestations, imaging examinations (X-ray, CT, MRI, etc.) and pathological examinations. 1. Clinical manifestations: Bone tumors such as osteosarcoma are mostly seen in adolescents, and more than half of osteosarcoma onset age is below 20 years old; the main symptoms are pain, swelling, and movement disorder. Chondrosarcoma is mostly seen in middle-aged and old people, with pain as the main symptom. Malignant tumors almost always have localized pain, which starts as intermittent and mild pain and later develops into persistent severe pain, nocturnal pain, and may have pressure pain. Pathological fracture is the first symptom of some bone tumors and a common complication of malignant bone tumors and bone metastatic cancer. 2.Imaging examination (1) X-ray examination: it can reflect the basic lesions of bone and soft tissue. Tumor destruction in bone manifests as osteolytic type, osteogenic type and mixed type. (2) CT scan, ultrasound, MRI, ECT: commonly used for tumors occurring in the pelvis, spine and other parts of the body, which can help to identify the location and scope of the tumor. (3) Isotope bone scan: it can show the existence of primary and secondary bone tumors before there is any positive change in ordinary X-ray, so bone scan with 9mTc should be done selectively for the suspects. 3. Pathological examination: the final diagnosis of malignant bone tumor depends on histopathological examination, and clinically, two methods can be chosen: incision biopsy and puncture biopsy. Pathological examination can determine the histological type of the tumor, clarify the benign and malignant nature of the tumor, in order to determine the surgical staging of the bone tumor, so as to formulate the treatment plan of the bone tumor. If there is any discomfort, one should consult the doctor in time and follow the doctor’s instructions for examination and treatment.