Abstract: In order to scientifically evaluate the Grain-for-Green Project and its soil and water conservation benefit, as well as other ecological benefit in the loess region, a vegetation investigation was conducted from July to August, 2005 in Wuqi County, Yan'an City, Shaanxi Province.By analyzing the data from 78 sample plots, we obtained the distribution laws of biotic crusts in the grain-for-green land of the loess region, and achieved some influencing factors, including disturbance degree, aspect, topographic position, slope degree, vegetation structure, vascular plants and microhabitat.Results showed that:1) coverage of biotic crusts on slopes with a low disturbance degree is larger than that with a high one, larger on north-facing slopes than that on south-facing ones, and larger on gully-slopes than that on ridge-slopes;2) coverage of biotic crusts increases with the increase in coverage and species of vascular plants, but will decrease after a critical number of vascular plant species;and 3) coverage of biotic crusts in a herb-dominated vegetation structure is larger than that in a tree-dominated one, and that in a shrub-dominated one is the smallest.