Effects of Caragana microphylla communities with different ages on protection and improvement of soils were studied.Results showed that with establishment and development of vegetation,soil physical and chemical characteristics of C.microphylla communities were improved obviously and there was a positive correlation between soil improvement effects and restoration time.Porosity and percentage of tiny sand (0.05～0.1 mm) and clay particle ( < 0.05 mm) increased,bulk density of top soil (0—10 cm) decreased,and saturated water holding capacity improved.The co ntents of organic C,total N,total P,alkaline N,available P and available K increased to some extent,especially in the topsoil,and C.microphylla exhibited a significant enrichment effect on higher nutrients under their canopies.