This study investigates the relationship between social participation, depressive symptoms, and cognitive function among middle-aged and older adults in China. Using data from the China Longitudinal Study of Health and Retirement (CHARLS) from Wave 1 to Wave 4, the researchers employed linear regression and generalized estimating equations to analyze the correlations. The results show that social participation is positively correlated with cognitive function, with the impact increasing with the variety of social activities engaged in. Depressive symptoms, on the other hand, are negatively associated with cognitive function. No significant interaction was found between social participation and depressive symptoms on cognitive function. After adjusting for covariates, social participation was found to affect cognitive function by reducing depressive symptoms, with the mediating effect accounting for 5.5% of the total effect. The study highlights the importance of social participation in enhancing cognitive function and reducing depressive symptoms, emphasizing the potential benefits of active social engagement for middle-aged and older adults.This study investigates the relationship between social participation, depressive symptoms, and cognitive function among middle-aged and older adults in China. Using data from the China Longitudinal Study of Health and Retirement (CHARLS) from Wave 1 to Wave 4, the researchers employed linear regression and generalized estimating equations to analyze the correlations. The results show that social participation is positively correlated with cognitive function, with the impact increasing with the variety of social activities engaged in. Depressive symptoms, on the other hand, are negatively associated with cognitive function. No significant interaction was found between social participation and depressive symptoms on cognitive function. After adjusting for covariates, social participation was found to affect cognitive function by reducing depressive symptoms, with the mediating effect accounting for 5.5% of the total effect. The study highlights the importance of social participation in enhancing cognitive function and reducing depressive symptoms, emphasizing the potential benefits of active social engagement for middle-aged and older adults.