With China's in-depth implementation of the domestic big cycle development strategy, digital co governance has become an important support to enhance the collaborative development level of urban agglomeration, reduce communication costs, and expand the collaborative radiation, and an important foundation to enhance regional and national competitive advantages. As the region with the best foundation for coordinated development in China, the Yangtze River Delta urban agglomeration has achieved rich exploration and practice in recent years in terms of digital co governance to help regional coordination. From the theoretical perspective of digital co governance and coordinated development of urban agglomerations, this paper analyzes the innovative practice of digital co governance of urban agglomerations in the Yangtze River Delta, and puts forward countermeasures and suggestions on how to innovate and explore the coordinated development mechanism of urban agglomerations under digital co governance in China.