Sand-dust storms occurred frequently in Northwest China in recent years. In order to forecast and prevent sand-dust storm occurrence, it is important to analyze the extent, magnitude and spatial distribution of sand-dust material source area. Aeolian erosion takes place on the bare surface of loosen material in arid and semi-arid regions, including cultivated land, low coverage grassland, sandy land, gravel Gobi, salinized land, and nude clay land. By using digital method of remote sensing and geographical information system techniques, TM images of the year 2000 have been interpreted to establish the database of sand-dust material source area in Northwest China. Based on studies and analysis of these databases, the following conclusions can be obtained: (1) In 2000, sand-dust material source area covers 138,612,007 ha in winter and spring, and 130,427,035 ha in summer and autumn. (2) In sand-dust storm source area, only 34.71% of land is used or usable, and the grassland occupies a large part of it. (3) In sand-dust storm source area, the strong aeolian land is almost equal to the weak aeolian land, and the extent related to dust is greater than that to sand. (4) The countermeasures are mainly to encourage farmers to spread straw on the land after harvesting until next planting season. The straw can protect the cultivated land effectively from aeolian erosion and keep the winter snow from freezing on these farmlands. (5) With the decreasing of water resources, cultivation practice in sand-dust material source area should be restrained to prevent the land from being aeolian eroded.