Abstract: China has entered a new stage of coordinated governance of pollution control and carbon emissions reduction. In the Yangtze River Delta Region, it is necessary to coordinately promote pollution reduction, carbon emission reduction and high-quality economic development to achieve carbon peak and carbon neutrality goals, and high-quality regional integrated development. In this context, the environmental policy synergies that promote carbon reduction, pollution reduction, green expansion, and growth are of great significance to the overall green transformation of economic and social development. 41 prefectural-level cities in the Yangtze River Delta Region were selected as samples to conduct an empirical study from 2006 to 2020. Taking the emission equivalent of atmospheric pollutants (including SO₂, NO_x , PM and VOCs), carbon dioxide emissions and high-quality economic development level as explanatory variables, and taking the intensity of pollution reduction and carbon emission reduction policies as the core explanatory variables, the synergistic effects of policies related to air pollution, carbon emissions, and high-quality economic development were tested by constructing a fixed effects model, and the mechanism involved was assessed by constructing an intermediary effects model. (1) The pollution reduction and carbon emission reduction policies had three significant synergistic effects. On average, for every 1% increase in the policy intensity, air pollution decreased by 0.470%, carbon dioxide emissions decreased by 0.292%, and the level of high-quality regional economic development increased by 0.040%. (2) The effects of the pollution reduction and carbon emission reduction policies were heterogeneous among regions. Only the core urban agglomeration achieved the synergistic effect of the three, while the central urban agglomeration only achieved pollution emission reduction, but had no policy effect on the peripheral urban agglomeration. (3) Two paths for energy consumption and green technology innovation were identified to achieve the three major synergistic effects of pollution reduction and carbon emission reduction policies. It is necessary to adapt measures to regional conditions differentiate policies, enhance policy synergy, and comprehensively achieve air pollution emission reduction, and high-quality economic development in the Yangtze River Delta Region.