This research analyzes the spatiotemporal development of city connectivity in China’s high-speed rail (HSR) network from 2008 to 2023, utilizing weighted degree centrality (WDC). The research examines connectivity patterns from a multi-scalar and typological regional perspective, focusing on national, regional, city-scale, and urban agglomeration levels. Research indicates a distinct “divergence-then-convergence” pattern. Specifically, initial development exacerbated regional and hierarchical inequalities, favoring eastern megacities and significant clusters, whereas subsequent network expansion enabled the gradual integration of central and western regions, medium and small cities, and inland agglomerations. The study emphasizes the dual function of HSR in improving overall connectivity while strengthening core-periphery structures and Matthew effects. It emphasizes the necessity for forthcoming policies that prioritize spatial justice, intermodal cooperation, and equitable infrastructure distribution.