1.X-ray examination Because soft tissue sarcoma is prone to distant metastasis and 80% of them occur in lung and mediastinum, chest imaging should be routinely performed. x-ray can also show bone destruction around the tumor and periosteal reaction, if there is bone destruction, it often indicates highly malignant sarcoma. Calcified dots only indicate that the tumor has had bleeding and necrosis and are not specific for diagnosis. If the tumor is translucent, it indicates the possibility of fat-derived tumor. 2.Computed tomography (CT) CT diagnosis of soft tissue sarcoma is characterized by non-invasive and stratified tumor image, and can also detect tumor and adjacent bone and muscle structures. Preoperative lung CT examination can detect early metastatic lung cancer. CT examination of retroperitoneal sarcoma can clarify the adjacent and invasive relationship between the tumor and important organs. For those who cannot perform MRI examination, CT angiography can be used to help preoperative tumor assessment and surgical planning. 3.Magnetic resonance imaging (MRI) Compared with CT, MRI can better describe the similarities and differences between tumor and adjacent tissues from multiple perspectives. However, MRI cannot be used to determine the benignity and malignancy of tumors. 4.Ultrasound Ultrasound shows that the mass is parenchymal or heterogeneous with abundant blood flow, which often indicates the possibility of soft tissue sarcoma, and is often used for the initial screening of soft tissue tumor. Ultrasonography is used clinically to diagnose and understand tumor size, boundary and relationship with its blood vessels. Ultrasound examination is also an important tool for postoperative follow-up, which can detect the recurrence of lesions at an early stage. 5.Arteriography The distribution of blood vessels in tumor can be understood by arteriography. Malignant tumors are rich in blood vessels and have disorderly distribution, while benign tumors have less blood vessels. Arteriography has a greater role in assessing the indications for limb-preserving surgery for tumors adjacent to important blood vessels. Benign hemangioma is not easy to identify malignant tumor because of its rich vascularity. 6.Isotope scan (ECT) For highly malignant soft tissue sarcoma, ECT examination is beneficial to screen the presence of bone metastases for early diagnosis and systematic treatment. It can also clarify the destruction of bone around the tumor by highly malignant soft tissue sarcoma, and if there is abnormal nuclein concentration, it often indicates that the tumor may invade the adjacent bone, which is of guiding significance for clarifying the scope of surgical resection and operation style. PET-CT can be used for prognosis, staging and evaluation of chemotherapy response, which is useful for evaluating tumor classification and guiding prognosis.