The economic circle around Beijing is a very important area that supports the development of Beijing-Tianjin-Hebei region in China. The economic growths of the economic circle around Beijing are deeply affected by the regional economic disparity. Besides the resources and environment problems, economic factors may be more prominent of regional sustainability. The objective of this paper is: (1) To find out what caused the regional economic disparity of Beijing-Tianjin-Hebei region; and (2) to assess the economic sustainable development status of the cities around Beijing, and give suggestions to narrow the regional disparity from the economic growth view. We used an assessment method based on the economic sustainable index system—the order relation method named G1 method, revised by standard deviation. The results showed that the fundamental reason for the differences lies in the disparity in production efficiency. The disparity in the regional economy increases the flow of talent to Beijing and Tianjin, so the labor productivity of Hebei Province will not improve. Thus, the economic gap among Hebei, Beijing, and Tianjin will continue to grow. This negative feedback will further exacerbate the economic growth problem. In terms of narrowing regional disparity, some implications are highlighted. Rational industrial structure, a high level of development in the manufacturing industry, and a high proportion of strategic emerging industries are important for the cities around Beijing to achieve high-level industry transfer, and the technological progress needed to promote economic growth.