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.