There are many causes of leg swelling in summer, the more common one is lower extremity vein thrombosis, which can cause significant swelling of the lower extremities with pain and other symptoms. Varicose veins in the lower extremities can affect the venous blood flow back to the lower extremities, which can also cause swollen legs. Trauma and infection of the lower extremities can result in exudation and swelling, which can also cause swelling of the legs. Severe cardiopulmonary disease and renal insufficiency, etc., can cause water and sodium retention in the body, which can lead to leg swelling. Most leg swelling in summer is caused by pathological factors, and patients should promptly go to a regular public hospital for examination and clear diagnosis. Since the causes of leg swelling are different, the clinical treatment is also different and should be tailored to the cause. Usually, we should avoid strenuous exercise and properly elevate the lower limbs at rest to help blood return to the lower limbs, which can relieve the symptoms of swelling.