Abstract In the context of an aging population, older adults increasingly face the challenge of managing multiple chronic conditions simultaneously. This study utilized analytical methods such as propensity score matching (PSM) and multivariate logistic regression, to explore the relationship between physical activity and the number of chronic diseases as well as the risk of developing co-morbidities among middle-aged and elderly Chinese individuals using data from the 2020 China Health and Retirement Longitudinal Survey. The PSM results showed that physical activity decreased the number of chronic diseases in middle-aged and elderly people by 0.050 (p