Lower extremity deep vein thrombosis is a chronic lesion left after the formation of lower extremity deep vein thrombosis, which is not treated promptly or incompletely, and the thrombus undergoes a repair process of mechanization, canalization and endothelialization, as well as obstruction, incomplete recanalization or complete recanalization. Also known as chronic lower extremity venous obstruction, this is quite a complex pathophysiologic process. There is no uniform time definite when the acute thrombosis is transformed into the chronic or sequelae phase. Generally, after 2 to 4 months, a slow pathological process is gradually entered. If the side branch vein is not compensated enough, and the deep vein trunk valve is destroyed, and a series of symptoms such as limb swelling and calf skin nutrition disorder appear, treatment is difficult, and the serious limb tends to be in the state of disease waste, and the patient’s quality of life is poor. The post-thrombosis syndrome of lower extremity deep vein is a clinical manifestation of venous hypertension in the lower extremity caused by obstruction of the main blood return obstruction and blood backflow due to valve destruction after recanalization. The syndrome after lower extremity deep vein thrombosis is caused by obstruction of deep vein causing obstruction of limb reflux, after repairing to achieve recanalization, gradually evolving to blood reflux leading to high pressure bruising in deep vein of lower leg, which not only causes gastrocnemius pump insufficiency, but also causes destruction of traffic branch valve, blood reflux into superficial vein and lower extremity edema; bruised tissue is hypoxic, metabolite accumulation, tissue malnutrition, leading to skin nutritional changes. The manifestations are heavy discomfort of the limb, aggravated after long standing or much activity; obvious swelling and pain of the affected limb, accompanied by intermittent venous claudication; limb swelling, increased muscle tone, superficial venous dilatation, pigmentation of the calf boot area, thickening and roughness of the skin, itching, eczema-like dermatitis, and the formation of chronic ulcers that do not heal or recur.