Abstract: Economic core regions are the main space of national and regional economic growth and urbanization development, but at the same time face the severe problems of urban sprawl. The integrated Changchun-Jilin(Chang-Ji) region is an economic core region on a national scale, a pilot of cooperative development and opening in Tumenjiang region, and the major grain producing region in northeastern China. It shoulders multiple responsibilities such as economic growth, urbanization of population and food security. Therefore, selecting Chang-Ji as a research object for the study of urban sprawl is representative and of great practical significance. Based on remote sensing images in 2000, 2005, 2009's and Almanacs of the related years, using GIS and SPSS statistical tools, we conducted a comparative analysis on the extent, process, effects and driving factors of urban sprawl of Changchun City and Jilin City. The results show that, (1) Changchun City has a higher level of urban land expansion than Jilin City; Jilin City shows significant stage characteristics. (2) In terms of the extent of urban sprawl, both cities show a low level of land use intensity and a high level of sprawling; in Changchun City industrial development and urbanization of the population are roughly in the same pace, but in Jilin City majority of the new land is used for industrial development. (3) In regard to the process of urban sprawl, Changchun City takes the process of "neighboring areas pushing on", while Jilin City shows a process of "axle band expanding". (4) As far as the effects of urban sprawl are concerned, both cities are negatively affected, e.g., loss of ecological and life security, rapid decrease of cultivated land; the severity in Changchun City is more striking, starting to show big-city problems. (5) Industrialization and investment are the main driving factors for both cities, which show typical government-oriented characteristics, with different factors contributing various effects. In summary, the paper points out that spatial expansion of urban land of Chang-Ji twin cities are projected to eventually go through the same "pie-style" urban sprawl as Beijing City. A simple economical and intensive land use policy can't fundamentally solve the problem, therefore it is suggested to promote intensive use within the cities and cultivate regional city clusters to form a system of urban cities of reasonable sizes.

Key words: Changchun-Jilin, comparative analysis, economical and intensive land use, principal component analysis, urban sprawl