Common malignant bone tumors of the limb include osteosarcoma, Ewing sarcoma, chondrosarcoma, etc., which are most common in adolescent patients. Although the incidence rate is not high (the annual incidence rate of osteosarcoma is reported to be 1 per million abroad), the death and disability rates are very high, which brings heavy psychological blow and economic burden to patients and their families, as well as huge economic pressure to the society. When malignant bone tumor of limb occurs, the traditional treatment is to choose radical or palliative amputation. However, with the progress of adjuvant therapy, especially neoadjuvant chemotherapy, the survival rate and limb preservation rate of limb malignant tumors have been greatly improved in recent years. The goals of bone tumor treatment are: tumor eradication, long-term patient survival, and limb preservation as much as possible. Bone tumor treatment is a complete treatment system. It includes preoperative – reasonable biopsy site and mode; clinical imaging pathology diagnosis; correct staging; appropriate adjuvant treatment including neoadjuvant chemotherapy. Intraoperative – selection of the correct resection method; tumor-free technique; reasonable bone and soft tissue reconstruction. Postoperative – postoperative adjuvant treatment, including evaluation of preoperative chemotherapy effect, selection and adjustment of postoperative chemotherapy regimen, selection of radiotherapy and immunotherapy, etc.; and follow-up survival rate and limb function assessment, etc. Diagnosis of bone tumor】 The diagnosis of bone tumor requires a combination of clinical manifestations, imaging (including conventional X-ray, CT, MRI and DSA, etc.) and pathological examination. Except for certain benign lesions such as osteochondroma and osteoid osteoma which can be diagnosed by characteristic X-ray manifestations, most of them need the combination of clinical, imaging and pathology to confirm the diagnosis. Among them, pathological diagnosis is the gold standard of bone tumor diagnosis. Biopsy is an important part of bone tumor diagnosis and treatment, and is the only method to make a clear diagnosis before formal surgery. 1.Excisional biopsy: it can obtain enough representative lesion tissues and facilitate pathological diagnosis. However, incisional biopsy has the risk of hematoma and infection at the biopsy site and tumor contamination of the incision. There are also tragedies that patients with limb preservation conditions lose the chance of limb preservation and eventually have to choose amputation due to tumor contamination of the biopsy incision and tumor spread due to improper operation of physicians. For these reasons, the choice of excisional biopsy must be made by a specialist who will perform further radical surgery on the patient, and some teaching hospitals and research centers such as the Sloan-Kettering Cancer Center still perform excisional biopsy as a matter of routine. Standardized biopsy techniques are very important for the diagnosis and subsequent treatment of the disease, and blind biopsy should not be avoided. 2.Closed puncture biopsy: At present, most hospitals and professional doctors advocate closed puncture biopsy for bone tumor patients. The advantage of closed biopsy is to minimize the biopsy channel and reduce the scope of hematoma and tumor tissue contamination. Although the amount of lesion tissue obtained by closed biopsy is small, the diagnostic rate of the disease can still reach more than 80%-90% with proper operation. Closed biopsy is divided into fine needle aspiration biopsy and coarse needle drilling and coring method. the former is suitable for soft tissue tumors with rich cellular components, bone marrow tumors, etc.; the latter is suitable for substantial bone tumors. x-ray fluoroscopy, CT and B-US can help to locate and improve the accuracy and success rate of aspiration biopsy.