Rural population aging is a major social issue in China, but its impact on agricultural nonpoint source pollution has been largely overlooked by researchers. To explore the relationship between rural population aging and agricultural nonpoint source pollution, we used over 290,000 tracking survey data from the Rural Fixed Observation Points Survey (2003–2021), which is the most representative data set in China, and identified the long-term association between them. We found that rural population aging has a significant reduction effect on agricultural nonpoint source pollution, with each 1% increase in the proportion of elderly people in rural households reducing agricultural nonpoint source pollution by 0.0656%, and this reduction effect gradually weakening over time. This study provides a new perspective and evidence for developing effective policies to mitigate agricultural nonpoint source pollution.
