There are many causes of edema starting at noon and at night, which may be cardiogenic edema, nephrogenic edema and hepatic edema. It is necessary to clarify the causes of edema according to the location and symptoms and after perfecting relevant examinations. 1. Cardiogenic edema: the main cause is right heart failure, elevated pressure in the circulation, obstruction of blood return, and edema, which is often manifested as symmetrical depressed edema in the low-hanging parts of the body. Because of the activities in the morning, the edema in the low-hanging part of the body is more obvious at noon and in the evening. 2. Nephrotic edema: the main cause is sodium retention. It is divided into nephropathic edema and nephritic edema. Nephropathic edema starts from the lower limbs. Nephritic edema starts from the eyelids and face. Similarly, after the morning activities, edema is aggravated at noon and in the evening. 3. Hepatogenic edema: mainly due to portal hypertension, hypoproteinemia and other factors, mainly manifested as ascites, may also appear in ankle and other distal edema, while the head, face and upper limbs often have no edema. Cirrhosis is a common cause. Edema starts at noon and in the evening, which is usually caused by activities in the morning, especially more obvious in diseases manifested by edema in the low-hanging parts of the body. Early medical attention is recommended to clarify the diagnosis and standardize the treatment.