In recent yeas

the transportation of Beijing has made a great progress in building up of the ring roads

which have promoted the development of big commercial sites and estate surroundings

at the same time

brought up the change of land use.The objectives of this research are to detect the changes of land use from1988to2008and reflect the improvement of the ecologiˉcal environment

which is also the object to support the2008Olympic games.Considering the above two aims

and after stanˉdardized radiometric normalization correction and geometrical correction of the Landsat TM image of1988

1994

2001and2003in May or June

these images are classified by SOFM（Self Organized Feature Map of Neural network）method.Then the frequency index model

spatial autocorrelation analysis model and urban expansion potential model are adopted in this paper to analyze the land use change information extracted from the classified information.The analytical result of these methods show that from1988to2003the city expansion tendency is obvious.The transformation from farmlands to builtˉup areas is the main resource of urbanization

from2001to2003the green land increased between the fourth ring road and the fifth ring road

and from1994to2003the urban expansion potential index of Beijing city is increased by degrees from the inner fourth ring road to the sixth ring road.Based on all these analytical results we can draw a conclusion that the change character of land use with ring roads driven and the urban expansion process of Beijing city centering the old city and surrounding the ring roads in the past decade.