Lower extremity venous thrombosis is an abnormal coagulation of blood in the veins of the lower extremities due to a variety of reasons, which can lead to obstruction of venous reflux and edema of the limbs; the thrombus can be dislodged, leading to pulmonary embolism, myocardial infarction and other embolic diseases, which can be life-threatening in severe cases. It usually takes 2 days from the formation of lower extremity venous thrombus to the beginning of mechanization, and about 2 weeks to stabilize the mechanization. During this period, it can be easily dislodged. The femoral vein, iliac vein and other veins are thicker and have a longer chance to dislodge for a longer period of time, even up to about 1 month. During the period of venous thrombosis to complete mechanization, the thrombus is easily dislodged. And after complete mechanization, the thrombus is difficult to dislodge. However, it is important to note that venous thrombosis in the mechanized state is not absolutely non-dislodging, and it may also induce the formation of new venous thrombosis. Once a lower extremity venous thrombosis is detected, it is important to consult a physician to determine the condition of the thrombosis and to treat it aggressively under the guidance of a physician.