China is stepping into the developmental stage of fast urbanization. The important characteristic of urbanization and rapid development of economy is the sharp expansion of urban build-up area. The demand of urban land is getting larger and larger, however, it is impossible to meet the great demand unlimitedly due to the scarcity of land resources. The difficulty of urban land expansion is getting bigger and bigger, so the process of rapid urbanization is restricted by the shortage of land. The conflict between them becomes more and more serious; as a result, the research on the process of rapid urbanization and the regularity of urban expansion is popular in the academic world at present. This paper selects 222 municipal cities as samples, examines the general trend of urban land expansion from 1997 to 2007 based on rank-size law and fractal theory, and analyzes its diversity at different land scales and in different regions and provinces by calculating UEI （Urban Expansion Index）. The results are shown as follows. （1） The total amount of urban lands is keeping increasing in China, and in the case of 222 cities, the scale difference among cities is getting larger, and the general balance is keeping decreasing. （2） The larger the city scale is, the faster the expansion will be. （3） The expansion speed of eastern cities is greater than that of western cities. （4） The eastern coastal cities are developing faster, such as the municipalities directly under the Central Government, and those in Guangdong, Jiangsu, Zhejiang and Fujian. Finally, discussions are made on the mechanism of influencing factors from the viewpoint of physical conditions, administrative division adjustment, eco-nomic development and population growth.
Progress in Geography