The length of chemotherapy for osteosarcoma is closely related to the stage of tumor and treatment strategy. If the tumor has developed to advanced stage with extensive systemic metastasis, chemotherapy is the main means to control the tumor development at this stage and long-term chemotherapy is required. If the tumor is in the early stage, chemotherapy is only an adjuvant treatment plan, and the specific chemotherapy time is related to the surgery. Amputation surgery requires six cycles of adjuvant chemotherapy, which usually takes about six months to complete the postoperative adjuvant chemotherapy. Two to three cycles of adjuvant chemotherapy are required before limb preservation treatment. If the tumor cell necrosis rate is >90%, limb preservation surgery can be performed, and six to nine cycles of chemotherapy are required after surgery. If adjuvant chemotherapy is ineffective, it is mostly changed to amputation treatment, and 6 cycles of chemotherapy are required after surgery.