As an effective tool to curb urban sprawl, UGBs (urban growth boundaries) have been paid worldwide attention. According to the implementation mechanism, which is similar to their counterparts in Western countries, the planning urban construction boundaries can be defined as the Chinese UGBs, safeguarded by the latest Town and Country Planning Act enacted in 2008. There are quite a few examples in establishing UGBs. However, the determination of UGBs has not been based on sound scientific analysis in the previous cases. Especially, quantitative analysis was insufficient in the process of determining the boundaries. In this paper, the methodology of constrained CA (cellular automata) was introduced to support the establishment of the UGBs. Compared with traditional methods of establishing UGBs, constrained CA took into account more factors related to urban growth, and could make effective spatio-temporal dynamic simulation influenced by various urban development policies. Taking a case s...更多tudy of Beijing municipal area, we developed the UGBs in the central city, new cities and small towns. The results showed that there was large difference between the urban growth pattern simulated through constrained CA and that projected in the urban master plan. Consequently, the UGBs could be improved according to the simulation result based on constrained CA.