Abstract: The key to coordinated development of regional economy lies in the coordination between population size distribution and industrial structure optimization. Based on the panel data of 31 provinces (districts and cities) in China from 2011—2021, this paper empirically tests the impact mechanism of population size distribution on the coordinated development of regional economy. Research has shown that population size distribution promotes coordinated regional economic development; The optimization of industrial structure plays a mediating role in the coordinated development of regional economy through population size distribution; There is regional heterogeneity in the impact of population size distribution on regional economic coordination, with the eastern region showing a significant promoting effect. To this end, we need to improve the carrying capacity of central cities, build modern industrial ecosystems, and build regional development communities to promote coordinated regional economic development.