A method is designed in this paper to identify the urban rural fringe by combining digitally processed remote sensing images and abrupt change test. Firstly

the urban and use information is extracted from the TM images

then it is to calculate the proportion of the urban land use in a given size window on the map of urban land use

and moving the window to smooth the proportion. Finally the moving t test of abrupt change is used to detect the abrupt changes for the proportion of the urban land use in the urban rural sections in all directions

and to identify the position of the inner boundary and outer boundary of the rural urban fringe between the city and county. Using the TM images of Beijing City in 1984 and 1996

a case study is made to identify the urban rural fringe with the method mentioned above. The result indicates that the method is practicable.