Urban sprawl studies involve various subject areas, including the urban geography, economics, sociology and ecology, etc. and it is a common topic focused by the geographers, planners, environmentalists, land economists, etc. At present, the land expansion in most cities of China is too fast, presenting the extensive economic development and urbanization model of the land extensive operation. It is badly in need of theoretical studies on the urban sprawl. In this paper, the existing domestic and foreign theoretical studies on the urban sprawl are analyzed and evaluated, and combining the overall planning of Kunming City, the urban sprawl phenomenon in Kunming is analyzed.