The swelling of the feet after standing for a long time is mainly due to the high venous pressure in the distal part of the lower limbs after prolonged standing, which causes the fluid in the blood vessels to seep out from the vascular gap due to the excessive pressure, causing local subcutaneous tissue edema. Moreover, the loss of calf venous pump function after prolonged standing leads to venous stasis in the lower limbs due to obstruction of venous return, and these two conditions promote foot edema. There is also a pathological condition that is often involved, which is venous valve insufficiency in the lower extremities. Because the valve does not work to stop the regurgitation, it aggravates the edema after standing for a long time. Ultrasound should be performed once the edema after prolonged standing occurs to clarify the presence of pathological lower extremity venous valve insufficiency changes and treat accordingly.