Rapid urbanization is a growing threat to the eco-environment, and it has seriously restricted the regional social and economic development. Moreover, it has negative effects on the Regional Pattern for Ecological Security (RPES). We studied the Beijing-Tianjin-Hebei Metropolitan Region (BTH), which is one of the most typical agglomerations in China, as a case example to determine the influence of the increasingly changing regional landscape pattern on the future of the RPES. Therefore, we used land-use change to represent the urbanization process, and the distribution of ecosystem services to represent the RPES. It is our hope that this study would provide scientific evidence to support optimizing future regional planning and management. The results were as follows. (1) There was a marked change in the landscape patterns in the BTH, which was faced with the problem of imbalanced development. (2) The area of high and very high ecosystem services accounted for one-third of the total area of the BTH, including nearly half that contained more than two services. (3) The CLUE-S model was robust in its applicability for simulating the land-use dynamic changes of the BTH, and the kappa index was 0.84. The ecosystem services occupied by the artificial surface accounted for one-sixth of the new increased artificial surface, and the main occupied services were sandstorm prevention and water retention. Furthermore, the occupation mainly occurred in growing cities such as Beijing, Tianjin, and Tangshan. (4) The imbalanced development of the BTH would not only enhance the gap between different cities but would also increase the potential threats to the pattern of regional ecological security. Therefore, the ecosystem services that would restrict the urban expansion should be considered, and this would facilitate the protective strategies for the RPES and future coordinated development of the BTH.