Liposarcoma is a malignant tumor and liposarcoma is a benign tumor. ultrasound shows that liposarcoma has a more intact envelope and liposarcoma is more hemorrhagic. CT, pathology and other further examination are needed to confirm the diagnosis. 1. Liposarcoma: as seen by ultrasound, liposarcoma is often lobulated, round-like and rich in blood flow. It is usually a deep, painless and gradually growing mass. The peripheral part of the lobule is rich in cells. The interstitium is mucinous with a “reticular” capillary network. Interstitial hemorrhage is common. Surgical resection is needed. 2. Lipoma: It is a benign soft tissue tumor, composed of mature fat cells. It is slow-growing, with clear margins and smooth surface. There is a complete periphery, and the inner part of the periphery is homogeneous and medium intensity echo. It is slightly higher than the surrounding tissues and has no posterior echogenic enhancement effect. There is no abnormal blood flow signal around and inside the tumor. It is also usually surgically resected. Both lipomas and liposarcomas require medical attention and treatment as soon as possible to avoid further delay.