Urban agglomerations are important carriers of the current world economic development and economic center of gravity shift, while urban construction land structure reflects and influences the functions and development directions of urban agglomerations and cities within them. It is significant to study the characteristics of urban construction land structure in urban agglomerations. Based on information entropy model and shift-share model, this study discusses and analyzes the evolution characteristics and spatial allocation differences of urban construction land structure in Beijing-Tianjin-Hebei urban agglomeration, and simulates the spatial allocation differences with the help of GIS technology. The empirical research results show that from, 2006 to 2017, the overall structure of urban construction land in Beijing-Tianjin-Hebei urban agglomeration changes alternately between “orderly” and “disorderly”, and finally the overall development was slightly disordered. Furthermore, there are significant differences in the competitiveness of different types of land in different cities. Among them, green land, public facilities land, and road traffic land show obvious replenishment effect, which are mainly distributed in Handan-Zhangjiakou northwestern Hebei, Tianjin-Cangzhou in the eastern coast, Baoding-Xingtai in central and southern Hebei, while industrial land and storage land, which are mainly distributed in Beijing-Tangshan-Langfang around the capital and Shijiazhuang-Handan-Hengshui in central and southern Hebei, show obvious crowding-out effect. In addition, the temporal changes and spatial allocation differences of urban construction land structure are influenced by many factors, such as economic development, industrial structure, population size, etc. Therefore, it is suggested that the coordinated development of urban agglomerations should adhere to the principle of “differentiated development before coordinated development, local coordinated development before overall coordinated development”.