To investigate the influence of social factors on the water quality of rainfall-induced runoff in the main urban area of Chongqing City, this study analyzed the inter-annual variations in the water quality of rainfall-induced runoff under policy influences from 2010 to 2021 and conducted a correlation analysis of pollutant indicators of rainfall-induced runoff. The logarithmic mean divisia index decomposition model was employed to quantify the effects of population size, technological innovation, economic development, and industrial structure on the water quality of rainfall-induced runoff. The findings revealed an improving trend in the water quality of rainfall-induced runoff in the main urban area of Chongqing City, accompanied by enhanced correlation between pollutant indicators. The water quality of roof runoff in 2019 and pavement runoff in 2021 improved to the range of “slightly clean to polluted”. Suspended solids demonstrated significant correlations with COD, NH₃-N, TN, and TP