While the challenges posed by multi-dimensional boundary effects to global economic integration are studied widely, regional economic integration within a sovereign country requires additional analysis. The Yangtze River Economic Belt (YREB), a super-scale interprovincial area including three nested urban alliances, is a meaningful vision of regional economic integration in China. After building the producer services-based urban corporate network, this study investigates the influence of multi-dimensional boundary effects on regional economic integration by social network analysis and the exponential random graph model. The findings show that the fragmented reality of YREB’s economy is significantly different from the vision of the Chinese central government. More specifically, although the natural boundary restraints represented by distance have disappeared, multi-dimensional barriers to regional economic integration are still posed by administrative, policy, economic, and cultural boundaries. The estimation results pass the robustness test of the grouping sample of producer services. Therefore, we confirm that the multi-dimensional boundary effects, particularly the intangible ones, significantly impact regional economic integration even within a country with a top-down ‘strong’ governance.