<p>As a major regional economic policy, national development zones (NDZs) aim to promote China’s economic growth while also profoundly changing the spatial layout of cities. However, the effects of this policy urgently require comprehensive evaluation. Using the data of 225 cities from 2003 to 2017, this paper investigates the relationship and transmission mechanism among NDZs, economic growth, and urban sprawl using staggered difference-in differences (DID) model. The study finds that: First, the NDZs promote regional economic growth, but at the same time exacerbates urban sprawl. Specifically, the NDZs promote economic growth by increasing industrial scale, and increase urban sprawl by accelerating industrial and residential land development. Second, for NDZs with areas ranging between 500&#xa0;ha and 1500&#xa0;ha, the government faces a more difficult trade-off between the goals of promoting economic growth and optimizing urban layout. In the eastern city, the NDZs have a more significant impact on economic growth, while in the western city, its impact on urban sprawl is more pronounced. In addition, economic and technological development zones (ETDZs) contributes more to economic growth, while high-tech industrial development zones (TIDZs) has a greater promoting effect on urban sprawl. Finally, according to the result of the threshold effect, moderate urban sprawl can fully unleash the economic growth-boosting effect of NDZs. This study helps to accurately assess the impact of NDZs on urban economic growth and spatial structure, and provides some policy directions for the promotion of high-quality economic development and new urbanization.</p>