It is of great significance for coordinated development to analyze the urban expansion process and urban connection characteristics of urban agglomeration. We studied urban expansion extraction and urban connection analysis methods for urban agglomeration based on remote sensing satellite sensors of thematic mapper (TM), enhanced thematic mapper (ETM+), operational land imager (OLI) and visible infrared imaging radiometer suite (VIIRS), and urban area extraction and multidata analysis technologies. Using the relevant materials of domestic land cover data and nighttime light data combined with population and economic data, we analyzed urban agglomeration characteristics of the Beijing–Tianjin–Hebei region, which is one of the most important urban agglomeration areas in China. The expansion characteristics of the Beijing–Tianjin–Hebei region from 2000 to 2021, as well as urban connection characteristics and their changes among the cities, and the three axes of Beijing–Tianjin, Beijing–Baoding–Shijiazhuang, and Beijing–Tangshan–Qinhuangdao were studied. The results show that: (1) the Beijing–Tianjin–Hebei region expanded largely during 2000–2021 and the comprehensive development gap narrowed. (2) A development trend has occurred around Beijing marked by an obvious border construction feature. The expansion speed of the capital metropolitan area was faster in the east and north and weaker in the southwest. (3) The connection of the three development axes was significantly strengthened since 2017, with two cores of Beijing and Tianjin. Some problems of uneven urban connection and uncoordinated development were noted in the Beijing–Tianjin–Hebei region and some suggestions have been addressed.