Abstract: The elastic membrane of rAts ascending aorta,thoracic aorta,abdominal aorta and common iliac artery at developing and aged has been observed with CLSM.At the same time,the area of the wall and the cavity of blood vessels,and the thickness of the tunica media have been observed with LM.During the aging,the microstructure of the ascending aorta,thoracic aorta,abdominal aorta and common iliac artery changed,such as the fluorescence intensity of the elastic membrane,the area of the wall and the cavity of blood vessels increased dramatically,and the tunica media thickened clearly.Corresponding to the variations of the structure,the arterial function changes greatly during the aging.