The examination program of renal atrophy is mainly clarified after measuring and evaluating the size of bilateral kidneys by abdominal ultrasound. It is also better to check the renal function indexes as well, to exclude renal atrophy caused by renal insufficiency. B-mode ultrasound examination of renal atrophy and kidney size includes the long diameter of both poles of the kidney and the thickness of the renal parenchyma. Adult kidney long diameter is roughly 10~12cm, width 5~6cm. usually <10cm can be counted as renal atrophy. The volume of the kidneys of the elderly shrinks with the increase of age. Renal atrophy is caused by a variety of reasons for the decrease in kidney volume of the pathologic anatomy of the definition, not the classification of diseases, the diagnosis of more than imaging tests on the size of the kidneys and other measurements and combined with the clinical diagnosis of the disease category. If renal atrophy is found in the auxiliary examination, it is recommended to go to the hospital in time, improve the renal function and other related laboratory tests under the guidance of the doctor, to clarify the cause, and actively treat the disease to avoid delaying the condition.