With the acceleration of the urbanization and industrialization in China, it is inevitable that arable land converts to built-up areas for industrial and residential uses. The urbanization rate has increased form 17 percent in the late 1970s to 39 percent in 2002. As we all know, during the end of 1980s and the beginning of 1990s, China has experienced a rapid urban growth, which was the so-called "great mass fever" on real estate development and establishment of Development Zones. However, compared with the developed countries whose urbanization rate exceeded 70 percent in general, China has a long way to go toward urbanization according to the theory of urban development. Thus there will be more arable land conversion in the future, which would impose pressure both on food security and on the sustainability of urbanization itself. In view of this, the spatial-temporal characteristics of arable land conversion and its driving forces of the large-scale cities in China in the 1990s are of importance to be analyzed. Based on the three-time Landsat Thematic Mapper (TM) digital images and statistic data of Beijing, it analyses the arable land conversion and its driving forces in this paper. Some conclusions were drawn as follows: During the early-1990s to mid-1990s, the rate of arable land converting to built-up area in Beijing is 14.4%. Of all the converted arable land, 45.7% was converted to built-up area and 90.6% was converted from arable land in all the new built-up land. Accordingly, the figure is 4.60/9, 52.1% and 80.7% respectively in the latter period. Arable land conversion to built-up land played an important role in cultivated land losing. At the same time, factors such as population increase, development of the national economy and changes of urban development planning had significant effects on this conversion.