Swollen feet in summer, may be related to physiological factors, may also be caused by pathological factors, if it is unilateral consideration of lower extremity vascular lesions, bilateral is more likely to be renal insufficiency, liver disease or cardiac insufficiency and other causes. 1. Physiological factors: Staying in a too hot environment for a long time leads to vasodilatation of the feet, which may cause slight swelling of the subcutaneous soft tissues of the feet, which is a normal physiological phenomenon and does not require special intervention. 2. Lower extremity vascular disease: Commonly seen in lower extremity varicose veins, lower extremity venous thrombosis and other diseases, may lead to lower extremity venous reflux is not smooth or blocked, may cause feet swelling, especially in the summer hot weather, the symptoms are particularly obvious. 3. Kidney diseases: such as glomerulonephritis, nephrotic syndrome, renal failure, etc., may lead to renal failure, resulting in weakening of renal filtration capacity, which may cause swelling of the feet, especially in the summer when the symptoms of swelling of the feet are more serious. 4. Liver diseases: such as cirrhosis, chronic hepatitis, etc., may lead to a decrease in the albumin index in the patient’s body, resulting in a large amount of water to the local tissue gap infiltration, which may cause swelling of the feet, especially during the summer feet swelling is more obvious. 5. Cardiac insufficiency: when the patient’s heart is not functioning properly, the right heart does not return enough, resulting in venous circulation stagnation, which can also cause swelling of the lower limbs. In addition, drugs, rheumatic immune system diseases, hormone secretion, etc. may cause lower extremity swelling of both feet, after excluding physiological factors, should seek medical advice as soon as possible, after clarifying the cause, and comply with the doctor’s instructions for treatment.