Natural disaster such as the large flood took palce in 1998 in China and the dust storm in 2000 around Beijing makes our government paying more attention to improve the ecological environment in China. In order to improve the ecological environment

a great deal of the dry land must be returned back to forest or grass land. Where the dry land must be changed inlo the forestland or grassland is a very important question.In our study GIS is used to find the place where the dry land must be changed into forestland or grassland. In includes four steps. Firstly

the database is extablished including land use database

soil erosion database

DEM

slope database

aspect database

normalization vegetation index （NDVI） database

precipitation database and temperature database. The ecological environment quality database is oltained thtough evaluating the ecological environment quality. Secondly

the dry land from Landuse database was overlain with slope database

soil erosion database

normalization vegetation index（NDVI） database and the ecological environment quality database. The distribution of the dry land of different slope was analyzed. The distribution of the dry land of different slope under different soil erosion

different NDVI and different ecological environment quality was also analyzed. Thirdly

the expert knowledge about the dry land was collected

and a model of finding suitable places for changing into forestland or grassland is formulated on the basis of the knowledge. Finally

the suitable places are overlain with the precipitation layer to decide where trees need to be planted or where grass need to be planted. It shows that the results provide an important scientific decision base for government to construct the ecological environment in China.