This paper examines sectoral growth patterns across Chinese provinces during the country’s economic takeoff in the early 2000s, following major policy reforms including trade liberalization, infrastructure expansion, business climate improvements, and relaxed rural-to-urban migration restrictions. We develop a multi-sector, multi-region spatial general equilibrium model with heterogeneous firms á la Melitz-Chaney to analyze how these reforms interacted to shape regional economic growth. We quantify the model for the Chinese economy and conduct counterfactuals to identify the key mechanisms driving regional development. We find that reductions in trade costs and lowered entry barriers facilitate firm entry and intensify competition. Together, these factors shape regional specialization and China’s overall economic growth. Our decomposition exercises reveal that lowered business entry costs played a larger role than the reduction in trade costs in promoting the growth of real wages, especially in inland provinces. This operates through a selection effect, where more productive firms expand and force the least productive ones to exit, and through increased variety, which effectively lowers the price index.