By means of located monitoring and comparatively analysis，soil water deficient situation，soil moisture dynamic variation laws, soil aridizations and soil water compensation features under condition of different artificial vegetations have been studied in 35-45°steep slope of loess region in North Shaanxi. The results showed that: soil water was extremely deficient under condition of perennial artificial vegetations in steep slope. soil water storage (0-10m) was only equal to 26.2%-42.0% of field capacity in dry years, and in rainy years it was also only equal to 27.0%-43.3% of field capacity. The order of soil water deficit was: Caragana microphylla> locust> alfalfa> Chinese arbor-vitae> poplar> Chinese pine> wild land> apricot> Chinese date> farm land. Annual variations of soil moisture with same vegetation were weakened with soil depth increasing, and happened mainly in 0-200 cm soil layers. In same growth season, all CV (Coefficient of Variation) of soil moisture under different vegetations were bigger and concentrated comparatively in 0 -120 cm soil layers, but difference of CV in different vegetations was small; below 120 cm soil layers, CV were smaller, but difference of CV in different vegetations was bigger. Permanent soil dry layers always happened under condition of perennial vegetations in steep slope, but the difference of soil aridization intensity was obvious among different vegetations and growth years. Soil water compensation and recovery depths in rainy season were 1.0 -1.4 m, but the soil water storage increment and compensation degree in different vegetations were dramatically different. Soil water compensation depth in same vegetation in rainy years was increased over 60 cm than in dry years, while the soil water storage increment in 5 m soil layers was increased over 3 times. Under natural precipitation, the soil water deficit in artificial vegetations in steep slope cannot be reduced, soil aridization also can't be relieved.