How Does Internal Migration Affect Beijing–Tianjin–Hebei Cities?

As China’s regional development enters a critical stage of population redistribution and urban transformation, the impact of population mobility on regional demographic structures and urban functional restructuring has become increasingly prominent. Against this backdrop of accelerating Beijing–Tianjin–Hebei integration, cities of varying types have been confronted with growing complexity in demographic transitions and socioeconomic stratification during their processes of absorbing or exporting populations. This study employed microdata from the National Bureau of Statistics to construct migration flow matrices and utilized a decomposition quantification approach to explore the impact of internal migration on the population structure and quality in 13 cities within the Beijing–Tianjin–Hebei region. The findings indicated that, while Beijing has achieved some success in population control, it overall exhibits a “large inflow and large outflow” pattern. Langfang has attracted a large number of highly educated individuals and male migrants under the spillover effect from Beijing. Shijiazhuang’s population attractiveness has increased, yet the outflow of highly educated individuals remains unmitigated. Meanwhile, the internal migrant structures in industrial cities such as Tianjin and Tangshan have undergone significant changes following the industrial transformation. Cities in the passive outflow area and agricultural transformation area have experienced siphoning effects, but they face different potential risks due to their unique characteristics. This study further enriches the understanding of the impact mechanisms underlying domestic population mobility and provides differentiated policy references for cities to reconcile their development objectives with demographic realities.