The system of wind defense and sand dune stabilizat ion, which crossed the Tengger desert and was began to construct in 1956, has insured the Baotou-Lanzhou railway straightway for almost half century.During succession of soil-plant system for decades, a artificial system of Hedysarum scoparium + Caragana korshinskii + Artemisia Ordosica-Ari-Sandic Entisols has developed into a semi-natural and natural system of Artemisia Ordosica+ Bassia dasyphylla + Eragrostis poaeoides-Hap-Orthic Aridisols.Development of biocrust and crust horizon changed redistribution of precipitation.A drought horizon formed in 20~500 cm depth because of shrub transpiration.Low plants began to compete water with grasses and shrubs.Shrubs with deep roots obtained hardly rainfall supply and dropped out protection system gradually.Soil-plant system went to a thinner active horizon.All of the changes were affecting the structure and function of the whole protection system.