Usually, old blood clots in the lower limbs do not require special treatment, but they should be actively prevented by lifestyle changes. Usually, old blood clots do not dissolve completely and can affect the return of blood from the veins. However, they are generally not life-threatening. Old clots in the lower limbs have become smaller and harder and are tightly packed in the inner walls of the blood vessels, so that blood can still flow through them. Reduced space within the blood vessels may cause the blood to return to the veins at a slower rate, resulting in the recurrence of new blood clots on the basis of old blood clots. Therefore, it is recommended that the patient learns about his or her own situation in a timely manner with the hospital based on the scoring criteria of VTE, and adopts a program for preventing thrombosis that meets his or her own practical needs. In case of superficial varicose veins due to old DVT, it is recommended to wear varicose vein stockings to improve the discomfort. Although old blood clots are not easily dislodged, they still need to be improved by self-adjustment. It is important to prevent the reoccurrence of thrombosis. In addition, it is recommended that patients strengthen physical exercise to enhance blood vessel tension, eat more vegetables and fruits to accelerate blood flow, and clean up impurities in the blood vessels to help avoid the reoccurrence of new blood clots.