In this paper, 6 phrases of satellite images include Corona、TM、SPOT、ETM+ data which represent the information of Changshu of 1966, 1984, 1992, 1999, 2000, 2001 respectively were dealt with multi-band composition, image enhancement, precision emendation, interpretation index establishment, computer assistant visual interpretation.Vector maps of expanding towns of Changshu City from 1966 to 2001 are made by interpreting images above.The statistical result shows that the area of city is 6.4 times bigger in 2001 than in 1966.From 1984 to 2001, it becomes bigger and bigger of average area of town of every person for 24 towns.In expending space, city expending is affected by geography, physiognomy condition, economic level and policy decision-making.Extending directions of most of towns are accordant with the main rivers and major roads.There is significant difference in amount and relative rate in the extending among 24 towns, and there is geographic disciplinarian in the distribut ion of towns at different expending levels.Most of towns that have large expanding rate have convenient communication, but towns that have low expanding rates are far from major roads and rivers.According to many years statistics of city expanding and historical social and economic data, it is found that city expanding is related to rural urban migration, GDP and original dimension evidently, while is not to total population, total families, total industry production and total employee.Through the statistic, we found that there is significant difference in the values of GDP of per urban area among 24 towns.