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Chaohu, a lake located in the middle of Anhui Province, with the water system to left bank of Yangtze River, the range is between latitude 30°58’00’’ to 32°06’00" N and longitude 116°24’30" to 118°00’ 00"E.Southeast of the area is Yangtze River, north of the area is watershed areas of Yangtze River and Huaihe River, northeast of the area is Chuhe drainage area. The drainage area is 13350 km2. Based on the field survey and geological data, the cardinal stratum of lake-bed is mainly composed of Xiashu loess in the late Pleistocene, so its possible age is 12000 years or so. According to the Textual Research of Chaohu lake, the area of old Chaohu lake is about 2000km2, and now, the area of Chaohu Lake is only about 800km2, 38% of its present, so the changes of lakeshore of Chaohu Lake is very fast.This paper analyzes the maximum area and changes of Chaohu Lake base on not only with the help of spatial analysis of GIS but also with the comparative study of RS images, relief maps, Geological map, historical preference, chorography, field survey and etc. It emphasize the maximum area and changes of Chaohu Lake, the branches of lake, the collapse of lakeshore, the old canal between Yangtze River and Huaihe River, the characters of the sites in the Zhegao River’s drainage area. We can come to the conclusions as follows:(1) For Landsat TM data has rich information, we analyze the image brightness curves of typical objects in Chaohu drainage area, and come to the bands that has high sensitivity to soil moisture content is TM4 and TM7. We
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