从1958年确定分散集团式城市布局,到2004年修编北京城市总体规划,建设环绕中心城的一圈绿环,一直都是首都城市规划部门不懈努力的方向。但在经济发展的驱动力下,作为城市图底关系中的非建设用地特别是绿地常常不受重视。尤其是随着近年来北京城市化进程的加快、城市建 From 1958 to determine the layout of the scattered group of cities, to rebuild the city of Beijing in 2004 master plan, the construction of a ring around the Central City Ring, has been the capital city planning department tireless efforts. However, under the driving force of economic development, the non-construction land, especially the green land, as the bottom of the city map, is often neglected. Especially with the acceleration of urbanization in Beijing in recent years, urban construction