Lines on the legs may be caused by swelling lines, wandering thrombophlebitis and other causes. Expansion lines are usually caused by excessive weight gain, rapid development of the body, etc. They are traces of fibers broken due to the pulling of the skin and are difficult to disappear on their own. They usually do not have much effect on health, but it is recommended that people with a large weight base should pay attention to their own habits and reduce their weight in a timely manner. In the case of wandering thrombophlebitis, the streaks are usually reddish and painful, and usually occur on the abdominal wall, arms, and lower extremities. It is usually associated with tissue ischemia and is characterized by the presence of continuous segmental thrombi in the superficial veins, localized pressure and pain, and redness and swelling of the surrounding skin. It is recommended to go to the hospital for timely examination and treatment for the primary disease, so as not to delay the treatment and lead to aggravation of the condition.