Three year experiment of 27kinds of alfalfa-crop rotation was conducted on the 10-year-old alfalfa grassland in the arid region of Southern Ningxia Hui Autonomous Region.Dynamic characteristics of soil nitrogen,phosphorus and organic matter during the three years of alfalfa-crop rotation were studied.Results showed that in comparison with continuous alfalfa planting,organic matter continued to decline during 3years of alfalfa-crop rotation.Potato in the first and third year planting and spring wheat in the second year planting influenced soil matter content obviously The pattern of potato succession cropping made soil matter content to decline most seriously. Change in soil total nitrogen under different alfalfa-crop rotations was obvious,comparatively.The sole rotation patterns of cereal grain planting,such as millet or spring wheat pattern,was in preference to consumesoil total nitrogen.As a whole,soil alkali-hydrolyzed nitrogen content under different rotation patterns tended to decline and was directly influenced by the level of rotation crop yield.Soil total phosphorus presenteddeclining at first,then rising,and again declining.The alfalfa-crop rotation pattern can improve soil nitrogen and phosphorus effectiveness.So,the reasonable alfalfa-crop rotation pattern should be adopted for a highly efficient,harmonious and sustainable utilization of soil water and nutrient.