Urban system is the spatial reflection of the inner-deep social economic movement. New economic circum stances not only make the evolution of urban system present one brand-new landscape, but also put forward a new subject for planning of urban system. This article analyzes the properties of the traditional economic process and its essential ef fect on urban system; it makes a complete survey on the properties of new economic circumstances and its effect on re-forming of urban system; the complicated influential process and result are concluded into the aspects, such as new growth motive force, new economic organization, new location factor and new spatial phenomenon, and its inner effect mechanism is shown as well. In this article, the change process of urban system space is explained in four aspects: (1)dissimulation in the process of spatial agglomeration and diffusion; (2) change of “center-periphery ”effect; (3) acceleration growth of axial regions; (4) re-forming of the world and regional urban system. Based on the above theoretical analysis and the properties & requests of new economic circumstances, this article finally puts forward four philosophies emphasized by urban system planning, and forms the new frame for drawing-up of urban system planning.