Land resources not only provide support for urban development, but play a feedback and restricting role in unregulated urban growth. Taking Beijing City as an example, this paper analyzes supply and demand relationships and upper limits for the growth of land resources during the process of urban development. By analyzing dominant factors and trends in the demand for land resources, this paper gives preliminary estimates on the minimum size of the land demand in Beijing in view of constructing a World City. According to the basic characteristics of supply and demand relationships for land, current land use in Beijing is confronting a grim situation of conflict between supply and demand. We also point out maximum growth and three types of constraints on land resources. Last, we propose solutions to resource and environmental bottlenecks, and urban disease amid urban development.