Abstract: As an important concept of the resource management and environmental impact assessment , ecosystem integrity is mainly used to reflect the degree to which an ecological system maintains its structure, function and stability under external disturbance. The Minle-Yumen Section of the 2nd Double Line of Lanxin Railway was chosen for case study using the technology of remote sensing and GIS to elaborate how fragile the ecosystem along the line was and to evaluate impact of the construction on ecosystem integrity in the eco-fragile area of Northwest China. Results show that along the railway exist numerous types of ecosystems including shrubbery, desert, steppe, meadow, marsh, alpine vegetation, farmland, etc., all of which were moderate or high in ecosystem fragility. The impact of the construction on desert ecosystems was the highest and on marsh and alpine vegetation ecosystems relatively low. Within the radius of 10 km alongside the railway, the area with alienated and damaged ecosystem accounts for less than 0.5% of the total area of the same ecosystem. So it could be concluded that the general impact of the construction is relatively small on the ecosystems along the line. Lanxin Railway 2nd Double Line|ecosystem integrity|ecological fragility degree|impact assessment