Abstract: Based on the data of China Household Finance Survey (CHFS) in 2017, this paper constructs the household debt risk index from three aspects of debt pressure, debt paying ability and macro economy, and empirically studies the impact of population aging on household debt risk and its mechanism. The study found that population aging significantly curbed household debt risk, and this basic conclusion remained robust after changing the criteria for the classification of the elderly population and adopting the IV estimate of health workers per thousand. The mechanism analysis shows that population aging can influence household debt risk through household wealth accumulation and debt reduction. Further analysis shows that the impact of population aging on household debt risk has a typical group characteristic, and has a more profound impact on urban, low education, high income and middle-aged groups.