Abstract: The natural gas transmission project from Shannxi to Gansu Provinces exends across the southern edge of Mo Us sandy land and the Loess plateau in the east of Gansu Province.The ecological environment of the area along the gas pipeline is extremely fragile.Based on analysis of the present ecological environment condition along the gas pipeline and forecasts of influence of the gas transmission project on the environment,construction of the project would give rise great damage to the vegetation and exposure of sandy ground surface and loess,and change of the soil structure along the gas pipeline.Thus the soil erosion index of 20 m range along the gas pipeline would increase by 2 to 4 times,and soil erosion rate increase from 8 560 t/(km2.a) before the construction to 34 240 t/(km2.a)，which should bring about expanding of land desertification and intensification of soil erosion of the area along the gas pipeline without effective preventive and protective measures.