Abstract: As urbanization continues to deepen, urban development is facing new challenges in its sources of momentum and profound changes in spatial organization. Under the traditional growth-doctrine model, cities relied primarily on rapid industrialization, rapid urbanization, and the extended momentum of real estate development; their dynamic spaces were mainly expressed through new towns and new districts. As cities enter an era of structuralism led by urban renewal, however, both urban dynamics and their spatial carriers are undergoing fundamental transformation. From a historical-comparative perspective, and in light of strategic planning practices at different stages, this paper argues that urban dynamic spaces are a key factor shaping planning transformation. In the new era, the main sources of urban development momentum include innovation driven by changes in modes of production, consumption and cultural momentum generated by changes in lifestyles, and network momentum enabled by information-technology transformation. The new dynamic spaces corresponding to these functions, together with the growth laws of their built environments, will exert a major influence on urban spatial development.