The normal kidney is stable in retroperitoneal position due to the fixation of perinephric fascia, fat capsule, kidney tip and abdominal pressure, but the normal kidney can also have a certain limit of range of motion, such as 2~5 cm up and down movement when breathing, and 1 cm range of motion when changing posture in lying and standing position. Diagnosis: If the kidney has an excessive range of motion, the kidney is too low in the standing position, and the range of motion is more than 3 cm that is renal prolapse, if the kidney moves in a large distance across the midline to the opposite side that is wandering kidney. Ultrasound performance: prone or supine position, with the lower pole of the kidney as the fixed point, and then take the standing as, if the lower pole of the kidney moves down more than 3 cm or more than one vertebra is prolapse. The kidney has a wide range of movement and can move to the opposite side of the abdomen by changing the position, which is the wandering kidney. Some may have low back discomfort or back pain, which is aggravated by labor or prolonged standing, and some may feel a lump in the abdomen by themselves, bringing unnecessary tension. The vast majority of prolapsed kidneys and wandering kidneys do not require treatment.