The paper takes the downtown district in Xi'an as object of study, chooses CBHI and CBII as the quantification index, adopts the exponential method to define CBD range and analyses the fundemental structure of CBD Land Using. By comparing with the coastal city, We summarize the basic charactoristic of CBD sturcture and layout of the inland super-large city and put forward countermeasure of building CBD further and promoting the inland city's coordinated and quick growth.