The Research On The Relationship Of Commute Distance And Urban Space Extension

China is currently being in high-speed urbanization development period, the process of urbanization is speeding up. With urbanization increasing, the State city development strategy of "the control of Metropolitan, reasonable development of medium-sized cities, actively developing small cities " is facing new challenges. In fact, big city size did not effectively be controlled, its growth remains quick, urban space extensive extension has generated serious land wastage. With the above background and current rail transit and intercity rail development, the article will discuss if the city exists an optimal size based on the commute distance limitation.By a large number of domestic and foreign related literature review, the most research is concentrated in the urban transport and land development mutual relations. By the analysis of the impact-mechanism between the commuting distances and urban space expansion, the article shows the transportation accessibility is key bond between the commute distance and urban space extension. The improvement on transportation accessibility reduced commuting costs, so the resident's or firm's behavior of site impacted urban space extension.With the introduction of the urban economy area influence model in the end of this article and adopting related data of Beijing in 2000 and 2005 on the Beijing area the article has empirically been analysis influence between the outer suburbs and the metro-area, the results showed that at that period the degree of Beijing urban extension was greater to the west and north than to the east and the south. With the development of mass transit and commuter rate increases, even if the standard commute distance did not change, the actual commute distance will also increase.