Abstract: From 2019 to 2021,based on multiple remote sensing data,GIS technology,Fragstats,and AHP-fuzzy comprehensive evaluation model were used to quantitatively evaluate the landscape dynamics and fragile ecological environment of three periods (pre construction,construction,and operation) of long-distance pipeline construction in Tongjiang County,Bazhong City,Sichuan Province.The results showed the following:①The land use types in the study area were cultivated land,forest land,water body and wetland,and artificial surface,of which the area of forest land and cultivated land was absolutely dominant.From 2019 to 2021,the area change of the four land use types was significant in cultivated land and forest land.The dynamic degree change of artificial surface and cultivated land were the most obvious,the forest land was in the middle,and the dynamic degree change of water body and wetland was the most stable.②From 2019 to 2021,forest land was the main landscape type in the study area,accounting for more than 65%;cultivated land was the second largest landscape type in the study area,accounting for more than 30%;the water body,wetland and artificial surface landscape types occupy a small area.The proportion of forest land landscape and cultivated land landscape shows a slow rising trend,and the fluctuation range of artificial surface landscape was the most significant.Under the influence of human beings,a large cluster patch has been formed and was expanding year by year.③From 2019 to 2020,from the perspective of landscape scale,the degree of landscape fragmentation,landscape diversity and heterogeneity in the study area will rise first and then decline.With the completion of construction and the implementation of vegetation restoration,land reclamation and other measures,the landscape components will tend to restore the state before construction.④Most of the pipeline crossing sections were light and severe vulnerable areas.Due to the construction method and the implementation of ecological and environmental protection measures,the study area has not significantly increased the area of surrounding vulnerable ecological areas due to the construction of long-distance pipeline.