Research on Urban Agglomeration Spatial Optimization under the Background of New Urbanization:Four Urban Agglomeration of Sichuan as an Example

Urban spatial structure is one of the three major structures of urban system,and is the reflection of urban agglomeration's developing situation.It is the space projection of city's economic structure,social structure,hierarchical structure and functional structure.Urban agglomeration development will inevitably be along with the change of the spatial structure.This article will clear the connotation and basic elements of urban agglomeration spatial structure,the expansion principle and the main patterns.Then we will take the four urban agglomerations in Sichuan province as an example,through exploring the path of the Sichuan urban agglomeration spatial structure optimization,put forward the construction of urban spatial structure system of trinity.