The relationship between economic decentralization and regional economic growth has attracted wide academic attention. However, existing literature rarely explores the validity and applicability of decentralization theory from the perspective of location endowments. This study takes China’s county-to-city reform - a decentralization policy - as a point of entry to construct a decentralization model incorporating location endowments. Using county-level panel data from 1992 to 2009 and employing a difference-in-differences (DID) approach, the study evaluates the impact of county-to-city reform under the constraint of location endowments on county-level economic development. The findings reveal that the policy effects of local decentralization are constrained by location endowments. Specifically, in regions with poorer location endowments, county-to-city reform significantly inhibits local economic development. Indeed, mechanism analysis further indicates that in such disadvantaged regions, local decentralization under the county-to-city reform generates a “political resource curse” effect, which hinders economic growth through three channels such as distorted fiscal expenditure structures, corruption, and misallocation of land resources. The conclusions of this study provide a valuable perspective for understanding the conditions under which decentralization theory holds, while also offering rigorous empirical evidence for government agencies to design more targeted decentralization policies.