Chinese mega-city regions have become a new scale of capital accumulation and state regulation. In recent years these regions have attracted much scholarly attention; however, the growing research on regional spaces in China is marked by a lack of what we term “realpolitik” and an absence of rigorous case studies. This study uses the “politics of scale” to empirically investigate the realpolitik factors in the intercity railway planning process in the Pearl River Delta. To this end, we establish a two-dimensional approach to unravel the interscalar and intercity politics during this process. We argue that in an institutional vacuum, ad hoc measures have been frequently used to facilitate interscalar and intercity bargaining. This case study also establishes a new perspective for understanding China’s urban and regional transformation. Rather than treating the state as a passive agent, coping with the powerful forces of decentralization and market reform, we argue that the state has strategically redefined itself and has become even more sophisticated in its structures, functions, and tactics. The traditional one-sided and unidirectional approach to state-space analysis cannot adequately address these issues. A new perspective that considers the politics of various scales is needed to study the emerging state regime in China.