Abstract: In the Shapotou area along the both sides of the Baotou-Lanzhou Railway, after an effort in artificial sand-fixation and plantation made twenty-five years ago, the original drifting sand dunes have been completely stabilized and can easily distinguished from those drifting and semi-fixed sand dunes untreated. within the superficial layer of the artificially stabillizea sand dunes a kind of soil with A₀ and A1 horizons average 4.33 cm in depth have been formed. We call it fixed aeolian soil. The Soil-forming material is the finegrained substance originated from the drifting sand, which presents itself as ripples on the surface and as strata in the surface layer of the sand dunes. The soil crust with moss growing on it can resist the erosing force by withith a speed even as high as 25 m/sec. Therefore, in evaluating the effect in stabilizing drifting sand we should not pay attention only to the coverage of the vegetation on the sand dunes, but the status of surface soil and crust formed during the process of sand stabilization should also be an important criterion for the evaluation.