A pit on the leg is caused by sunken edema, which has both physiological and pathological causes. Physiological causes are more common in long-term standing caused by venous return obstruction, at this time through the elevation of the lower limbs, adequate rest can be restored to normal. Pathologic causes are more common in systemic diseases, such as primary glomerulonephritis, secondary nephropathy, heart failure, cirrhosis, malnutrition and so on. Neurogenic edema and venous dysfunction can also lead to lower extremity edema. If the edema does not disappear after resting or recurs, it is necessary to consult a doctor in time, improve the liver and kidney function, urine routine and other related examinations, to clarify the cause of the disease, and then carry out the appropriate treatment.