To study the impacts of pipeline construction on eco-environment in the middle-low mountainous area,the quantitative prediction is made for the changes of landuse,agricultural production,the area and biomass of vegetation,soil erosion,and ecological system integrity in the Daba Mountains by the Sichuan-Shaanxi natural gas pipeline construction.An analysis of possible influences made to the eco-environment of the middle-low mountainous area by the pipeline construction is then presented.Results show that the construction can change the structure of regional landuse,which can in turn influence local agricultural production,reduce the area and biomass of vegetation,and increase soil erosion.Nevertheless,the influences are temporary and can be alleviated,as they mainly concentrated in the construction period.The environmental effects of the project will not essentially alter the original eco-integrity of the middle-low mountainous area.Therefore,the ecological system remains its complete structure and consistent operating process.