Sclerotherapy, first proposed by Cassaigness in 1853, involves the injection of a chemical sclerosing agent into the varicose vein to cause a secondary inflammatory response in the vein wall, followed by continuous postoperative compression to cause the vein to atrophy and subsequent fibrosis of the granulation tissue in the lumen of the atrophied vein, eventually forming fibrous cords to treat the varicose vein atrophy. In the past, sclerosing agent (liquid) was mostly applied selectively to patients with mild varicose veins such as reticular varicose veins, capillary dilation or as an adjunct to surgery, and often could not be applied to the main trunk of saphenous veins. Foam sclerosing agent is a new foamy sclerosing substance formed by mixing liquid sclerosing agent with gas. In general, we advocate trunk ligation supplemented with sclerotherapy to avoid a series of complications such as deep vein thrombosis. In April 2003, the European Coordination Meeting on Foam Sclerotherapy was held in Germany, which considered foam sclerotherapy as one of the effective methods for varicose vein treatment and developed a definition of safe and effective foam sclerotherapy, allowing experienced physicians to apply foam sclerotherapy to treat large varicose veins, including saphenous trunks. The Second European Coordination Meeting on Foam Sclerotherapy, held in April 2006, concluded that the promotion of foam sclerotherapy has led to a revival of sclerotherapy as a minimally invasive treatment for varicose veins and that the use of foam sclerotherapy in various types of varicose vein disease is recognized worldwide for its safety and effectiveness. Among the many minimally invasive treatments for varicose veins in the lower extremities, foam sclerotherapy has a therapeutic effect on all kinds of varicose veins and has been proven in foreign literature to be safe, simple, economical, reliable, short hospital stay and repeatable, and has become a brand new method for treating varicose veins.