Abstract: In this paper, the characters of two kinds of urban structure, the concentric circles with single center and the spool thread with poly-centers, have been discussed. It is pointed out that the most ideal model of development of our city is the spool threadwith poly-centers by the viewof sustained development. The important inducing impact of rail transportation on the change of urban structure is discussed from the population, the environment and the land. At last, some problems of rail transportation have been shown from the present situation of our cities.