Valley economy, featured by valley development, is a new mode in mountainous area development, and prenents a distinguishing economic geographic pattern. The special spatial coupling relations in the distribution of different mountainous elements in valleys are new subjects for the mountain development studies, and such studies are meaningful both for researches and practices. Based on the long term researches on mountainous area development and following a brief exploration into the connotations and the spatial organizing process of valley economy, the authors analyzed the present situations of the development of valley economy in Beijing's mountainous areas, studied the characteristics and the impacts of the spatial structural changes of the valley economy in these areas, and finally proposed a rational arrangement of the spatial structure of the valley economy in Beijing. It is indicated that valley economy plays an important role in the development and functional transformation in Beijing in the new stage. Firstly, valley economy is not outlined by the administrative boundaries, and it connects most of the villages in the mountainous areas along the major transportation lines. Therefore, valley economy can exert positive influence on the development of the mountainous areas, at least in the aspects such as industrial restructuring in the mountainous areas and the coordinated development of rural and urban areas. In addition, it is found that the valley economy of Beijing has evolved in a spatial organizing stage of secondary concentration, which is characterized by resource-saving, ecological protection and industrial optimization. Therefore, the development of valley economy will be helpful to the coordination between ecological protection and economic development in the mountainous areas, and will promote the comprehensive development of these areas. The developing mode of the valley economy in the mountainous areas of China will provide the basis for the decision-making in the transformation of the functional roles of the mountainous areas of Beijing, and on the other hand, it will present experiences for the studies in the mountainous areas outside Beijing.