Urban expansion brought by the rapid progress of urbanization has caused many problems in China. It is a significant issue to evaluate the extent of urban expansion and to make appropriate controls over the sprawl of urban areas. With a comparative study of international experiences, this article analyzed the mechanism and consequences of urban expansion, reviewed the typical planning and financial policies adopted by other countries for controlling urban sprawl, and discussed the suitable densities of urban areas. The analysis results suggested that Chinese cities have no better choice but compact urban forms. To achieve the goal of compact development, intensive use of public transportation and high proportion of collective houses should be encouraged, and 60-100 m2 per capita is recommended as the reasonable range of urban density in large cities.