Renal aging is a main cause of the increase in the incidence rate of acute kidney injury and chronic kidney disease. Even in the absence of age-related comorbidities such as hypertension, the structure and function of kidney in the healthy elderly groups may degenerate, leading to increased kidney susceptibility to injury, insufficient repair capacity and pathological changes. Renal aging is a multifactorial regulatory process, clarifying the mechanisms behind may help repair the damage caused by acute kidney injury and chronic kidney disease. Published papers are reviewed in this article to demonstrate the process of kidney aging from aspects of cellular structural function changes and molecular mechanisms, so that more effective treatments can be found.