Abstract: This study was conducted in Loess Plateau of western Shaanxi Province, Northwestern China by taking Robinia pseudoacacia+Medicago sativa model as research object. Soil nutrients including organic matters, total N, available P and available K in 0-40cm soil layer were measured and analyzed, The distribution characteristics of these soil nutrients and their depth of edge influence were studied to provide theoretical basis for soil nutrients improvement, nutrient research of different land use types and management of silvopastoral system in this region. Results showed that: 1) The four nutrients indicators fluctuated on a large span in the silvopastoral system. The distribution characteristics of soil nutrient in different patches occurred difference to some extent. In general, the contents of soil nutrient indicators in Medicago sativa field were higher than those in Robinia pseudoacacia field. 2) Distribution characteristics of soil nutrients in Robinia pseudoacacia+Medicago sativa silvopastoral system were given as follows. The soil nutrient contents were higher in 0-20cm soil layer than those in 20-40cm, but the their changes were different. Horizontally, in the Medicago sativa field, apart from the content of total N without significant change, other soil nutrient indicators all increased with increasing distance from forest edge to grass area. Comparably, in the Robinia pseudoacacia field, organic matters, total N, available P decreased with increasing distance from forest edge to forest area, but available K showed an opposite trend. 3) According to the Principle Component Analysis, boundary soil nutrient in the silvopastoral system showed an edge effect of 4m in grass exterior to 3m in forest and a width of 7m.