In recent years, the spatial non-integration effect of administrative regions and economic zones existed in China, and as an important means of spatial governance, territorial spatial planning is the important foundation for the high-quality development of cross-regional. The research area is Beijing-Tianjin-Hebei agglomeration, explores the spatio-temporal change and driving mechanism of land development intensity, and embeded the adjacency relationship between county-level administrative units into the spatial econometric model to explore the influence mechanism of land development intensity under the different scenarios of administrative spatial spillover effect. The results show that the land development intensity of different county-level administrative unites were quite different in the Beijing-Tianjin-Hebei agglomeration, and the spatio-temporal differentiation and spatial agglomeration was significantly. The land development intensity of most county-level administrative units in the Beijing-Tianjin-Hebei agglomeration were improved, but the spatial pattern of "high in the southeast and low in the northwest" has not change. Population density, the proportion of tertiary industry added value and per capita GDP had significant effects on the land development intensity. The spatial distribution of land development intensity has significant positive spatial correlation, and the direct spatial spillover effect is obvious. From 2010 to 2019, the administrative spatial spillover effect of different adjacent relationships were different, and the spillover of adjacent relationships of different types of county-level administrative units was enhanced. In the future , we should make full use of the spillover effect of administrative space of land development intensity to achieve the sustainable development.