Baiyangdian lake is one of Largest lakes in the North China plain. Recently

its water area has gradually decreased year by year. Since 1984

this lake has almost dried up. The change of water body makes a notable impact on eco-environment and economy development in this region.In order to study on water body change

a geographically referenced data base of land cover of this area was compiled from topographic map at a scale of 1:50

000. The grid cell size is 250×250 metre. The airphotos and Landsat images for MSS and TM were acquired in same season

but different years （1961-1984）

and were optically transformed to the grids map using ZOOM Transformer. Meanwhile

the interpretation of each remote sensing image was conducted cell by cell based on seven coded categories of land cover. All data were entered into PDP 11/23 computer system. The graphics by compute processing were used to present the distribution and change of land cover. The result shows that the cultivated land has increased by 40

000 hectare

conversely the water area has want down 43333.3 hectare in this area from 1961 to 1984.Through correlative matric analysis which consisted of factors affecting the chang of water area in Baiyangdian lake

it can prove that the expanding of cultivated land and residential area have negative correlation with water area

the amount of entering water and the rainfall positively correlated with water area. Among which the correlation coeficient （R） between the amount of entering water and water area is 0.97. This demonstrates that the increase of water consumption of city industry and expanding of irregation area are important factor on the cutting-off for water supply and the drying up for water body of lake in dry season.