Sitting for a long time with swollen feet may be caused by physiological factors such as obstruction of venous return in the lower extremities, or it may be a symptomatic manifestation of certain diseases, such as venous thrombosis of the lower extremities, chronic cardiac insufficiency and so on. 1. Physiological factors: As a result of prolonged sitting, venous return to the lower extremities may be impeded and local blood circulation slowed down, thus causing the symptom of edema in the feet. 2. Lower extremity venous thrombosis: If there is thrombus formation in the lumen of lower extremity venous vessels, it may cause lower extremity venous blockage, which is clinically manifested as swelling and pain in the lower legs and feet. 3. Chronic cardiac insufficiency: if the heart systolic and diastolic dysfunction, the occurrence of body circulation stagnation, will show loss of appetite, abdominal distension, renal hypoplasia, edema and so on, edema is mostly seen in the lower limbs first. In addition to the above reasons, gout, tumors, kidney disease, liver disease, etc. may also appear the symptoms of swollen feet. If the patient appears to sit for a long time the symptoms of swollen feet and exclude physiological factors, it is recommended to consult a doctor in a timely manner, by the doctor to clarify the cause of the disease after targeted treatment.