More and more of the soil resources were occupied by the rapid urbanization in the Yangtse Delta. Based on the basic data of the TM images of four different periods, 1984, 1995, 2000 and 2003. This paper studies and analyzes the expansion of Suzhou City in the last 20 years using the method of multi-source information integration and multi-phase-successive-comparison with the aid of the technology of RS and GIS. Combined with the soil map of Suzhou and the data of the Second National Soil Survey, the results are used in exploring how much of the soil resources has been occupied by the expansion of the city. And impact of the expansion on safety of food supply is forecast.