In recent years, the soil deterioration whose characteristic is the land degeneration of the artificial forestry and grass lands is being worse and worse. And soil desiccation whose characteristic is critical deficit of soil moisture continuously is taken seriously. Soil desiccation can form dried soil layer, result in soil deterioration, slow down the velocity of vegetation growth, cause community declination and death, and imperil seriously ecological environmental construction in the no rth area of China, especially in the loess plateau. So, studying and solving dried soil layer have become the urgent task for the v egetation constructio n in the loess plateau. According to the soil moisture data of Yanan experimental area, dried soil layer of vegetation is analy zed preliminarily, the statuses of dried soil layers between the different forestry and grass plantation are compared, and the meaning of solving dried soil layer is put forward.