The treatment of soft tissue venous malformations on the body surface, especially extensive and complex venous malformations, remains a challenge due to the deep penetration into the muscle space, unclear lesion boundaries, and encapsulation of the main vascular nerve. Sclerotherapy is the mainstay of treatment for venous malformations and can be used with good results when properly applied. Sclerotherapy has a history of more than 100 years and is widely used because it is simple, safe, and has few complications. Commonly used sclerosing agents are sodium cod liver oil acid, ethanol, bleomycin (pinyamycin), polyglaucine, etc. The application of anhydrous ethanol and bleomycin is the most common. By injecting sclerosing agents, the endothelial cells and blood-forming fractions in the blood vessels are damaged, leading to thrombosis and endovascular inflammation in the luminal sinus, and later thrombus mechanization, fibrosis and vascular occlusion. After several sclerotherapy sessions, the deformed veins can be atrophied and the lesions can be reduced or even disappeared. In general, sclerotherapy is very safe, and the incidence of complications is very low. The main complications are: (1), if the venous malformation lesion superficially involves the skin, the skin on the surface of the lesion may produce blisters or even necrosis due to swelling and ischemia after sclerotherapy; (2), if the venous malformation lesion invades the interstitial muscle or the muscle, the injection may lead to muscle degeneration and fibrosis, affecting muscle function, but it can generally be recovered after exercise; (3), if there are nerve travels within the lesion, the sclerosing agent may damage the nerve leading to sensory-motor abnormalities. For the above-mentioned potential complications, preventive measures need to be taken preoperatively and intraoperatively, such as careful analysis of the imaging results before surgery to have a good idea of the location of the venous malformation and the surrounding anatomical relationship; for venous malformations with complex local anatomical relationship, the lesion can be accurately located intraoperatively with the help of ultrasound to avoid accidental injury. Our department has performed hundreds of cases of sclerotherapy for venous malformations, and the overall results are satisfactory. The following is a typical case.