Abstract: As the key construction area of Chengdu-Chongqing economic circle and the upper Yangtze River economic belt sustainable development, it is of great significance to diagnose the spatial and temporal variation of landscape ecological security degree in southern Sichuan urban for promoting the construction and ecological security monitoring of southern Sichuan urban. In this paper, the Google Earth Engine service platform and the programming language were used to obtain the land use classification data of validated accuracy in 2000, 2010 and 2020 from Landsat remote sensing images. Landscape disturbance degree was constructed by use of landscape fragmentation degree, separation degree on the basis of different dimensions, and landscape vulnerability degree was constructed according to land class sensitivity. The spatial distribution of landscape ecological security degree in southern Sichuan urban agglomeration was evaluated and analyzed by using landscape ecological security degree model and spatial statistics method, and the spatial differentiation law of landscape was studied using semi-variance function. The results showed that:(1)From 2000 to 2020, the landscape ecological security degree of southern Sichuan urban underwent a decreasing trend on the whole, with the spatial distribution showing a spatial differentiation of high ecological security degree in the east and west sides, and low ecological security degree along the Minjiang river and Yangtze river.(2)The Moran’s I values of global autocorrelation in 2000, 2010 and 2020 were 0.826, 0.806 and 0.803, respectively, and the scatter points were mainly concentrated in the first and third quadrants, indicating that the internal differences between high safety and low safety zones were small, and the spatial correlation was positive. (3) From 2000 to 2020, the hot spots of local autocorrelation were mainly distributed in Mount Emei scenic spot, Neijiang, Zigong and northern Luzhou, while the cold spots were distributed along the Yangtze River, the Minjiang River and along Yibin-Leshan-Luzhou urban development line. The spatial agglomeration level was unstable and the significance level was changing. The adjacent samples took on a gradual change from agglomeration distribution to random distribution. (4) The landscape ecological security degree of the southern Sichuan urban agglomeration exhibited significant spatial differentiation in 20a, which was largely affected by the joint impacts of structural factors and non-structural factors, of which structural factors such as topography, climate, soil and vegetation play a decisive role, while non-structural factors such as urbanization construction, traffic road construction and planting of cash crops such as tea plantation, forest and orchard exerted an important impact on landscape evolution. The research findings are of guiding significance for regional ecological construction and resource development.