The so-called foam sclerotherapy is to make a sclerosing agent (commonly used as polyglactin) into foam and inject it accurately inside the varicose vein under the guidance of imaging equipment to occlude the varicose vein and fibrosis, thus achieving the purpose of removing the varicose vein without surgery. This technique is an improvement of the traditional sclerotherapy technique and is becoming one of the preferred methods for the treatment of varicose veins because of its simplicity, safety, low cost and no surgical scar on the body surface. Foam sclerotherapy is preferred for the following types of varicose veins: 1) varicose veins of the lower limbs less than 0.6 cm in diameter; 2) varicose veins of the lower legs; 3) thick trunk varicose veins of the thighs, which should be sclerosed with ligation at the root of the thighs; 4) varicose veins that recur after saphenous vein stripping or laser treatment.