The reasons for having a lot of fine blood in the legs include varicose veins, venous thrombosis, age factor, and so on. 1. Varicose veins: Varicose veins are caused by various factors, which leads to the expansion of small blood vessels, and at this time, the phenomenon of many tiny blood lines on legs can appear. 2. Venous thrombosis: because of the obstruction of local blood circulation caused by venous thrombosis in the legs, the local small blood vessels will be dilated and the symptoms of tiny blood lines will also appear. 3. Age factor: when the age increases, the skin will gradually shrink, which leads to the exposure of blood vessels, so there are a lot of fine blood on the legs. Finally, if you have a lot of fine blood on your legs, please consult a doctor in time to find out the cause and follow the doctor’s instructions.