This paper takes Huai＇an as a case and analyzes the process of administrative district adjustment and its impacts on the evolution of urban spatial structure, and comes to conclusions that the influences of administrative division adjustment on the evolution of urban spatial structure can be divided into two types, the one is leading adjustment,-it means that administrative division adjustment can guide urban development direction, and affect the urban regional structure characteristics, the administrative district divided into Huaiyin County and Qingjiang City in 1964, and Huaiyin County resident moved to Wangying Town in 1971, it guided Huai＇an City north and south development for nearly 30 years. In 2001, the ＂three huai＂ administrative division adjustment, also guided main city to expand to southeast, and guided Chuzhou City to develop to northwest, after 10 years development, a new industrial space and eco- town have been formed between the two urban areas, and it strongly influenced the urban geographical s（-ructure. Another is adaptability adjustment, after the city developed to a certain stage, some structural and institutional contradictions in urbanization process can be solved by the administrative district adjustment, with the Huaiyin County merged into the main city in 2001 after the ＂three huai＂ administrative division adjustment, not only the problem of ＂city and county in the same city ＂ can be solved, but also the new growth space for the expansion of urban space can be provided, such administrative divisions adjustment can adapt to the reality of the integrated development of city and county. The mechanisms of administrative adjustment impacted on the evolution of the urban geographical structure can be attributed to the following aspects. The first, administrative district adjustment may change the urban jurisdiction, and then change the city economy scale and city development ability, which affect the urban geographical structure. The second, administrative district adjustment may led to the rapid change of urban form, urban population scale, and urban land use scale, and there will be more space fore urban expansion, the city government will arrange the urban development by the revision of the overall urban planning, and it will influence the evolution of the urban geographical structure. The third, after the adjustment of administrative divisions, spatial distribution of the town, which is merged together, can affect the direction of the urban development, and can guide the urban future development.