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Air pollution is an urgent global issue with significant implications for the environment and public health. This study focuses on the daily Air Quality Index (AQI) data from 27 major cities in the Yangtze River Delta (YRD) region of China spanning 2017-2022. Firstly, we establish an optimal threshold for constructing a stable AQI-weighted directed network, considering time lag coefficients and correlation coefficients. Quarterly analyses of correlation coefficients and time lag distribution among cities are conducted. Secondly, we apply complex network theory to examine the basic properties of the AQI-weighted directed network. Thirdly, integrating traditional methods and PageRank values, we identify crucial nodes, emphasizing key cities like Nantong, Nanjing, and Yangzhou in air quality management. Finally, utilizing the Louvain algorithm, three community structure divisions led by influential city nodes are dynamically identified. This study offers a valuable framework for collaborative air pollution management in the Yangtze River Delta, promoting improved air quality and sustainable urban development. [Display omitted] • An optimal threshold of θ = 0.782 is identified for constructing the AQI network. • Identification of key nodes for AQI-weighted directed networks. • Classification of AQI correlation networks into different association structures. [ABSTRACT FROM AUTHOR]