The causes of swollen legs after standing for a long time are as follows: 1, caused by vascular lesions in the veins of the lower limbs, such as the elderly due to poor venous reflux, or due to the degeneration of venous function, which can lead to venous reflux disorders in the lower limbs and the phenomenon of swollen legs after standing for a long time. 2, for patients with venous valve insufficiency, the phenomenon of swollen legs after standing for a long time can also occur. If leg swelling occurs after standing for a long time, we should check the lower limb vein ultrasound for early diagnosis, and pay attention to the lower limb can wear elastic stockings, which is beneficial to the elimination of leg swelling, while oral medication can be taken, such as horse chestnut seed extract tablets, which is beneficial to the reduction of leg swelling, and pay attention to the lower limb elevation at night when sleeping, which is also beneficial to the elimination of leg swelling. The cause of leg swelling should be identified and the cause and symptomatic treatment should be actively carried out.