Based on the investigation of soil seed bank,the soil organic matter contents and soil mechanical composition in different parts of sand dunes,so2called windward side,leeward side and lowland of sand dune,also the windward side parts,leeward side and the intersection of sand2barrier separately,where the sandy grassland in seriously desertificated and installed with high-banded sand2barrier of different years (2～3 and 4～5 years).The mechanism of high-banded sand2barriers for controlling desertification of grassland are studied by comparing with the same kind of places without sand2barrier.The result shows that installation of high-banded sand-barrier in seriously desertificated grassland can intercept seeds in sandy-driving wind,enriching seed bank,increase the contents of soil organic matter,decrease the coarse sand particles,increase the contents of minute sand parts in soil particlesize composition.