The continuous advancement of industrialization and urbanization has led to dramatic changes in land use / land cover, resulting in a series of ecological and environmental problems such as land degradation and ecological fragility. Based on the common characteristics of ecological security pattern under land use change in the future long-term sequence scale, and from the ‘anti-planning’ idea, the optimization strategy is an important means to deal with regional ecological security under the background of regional development uncertainty. Taking Chengdu-Chongqing urban agglomeration as the research object, based on the logic of ‘source extraction-resistance surface construction-corridor identification’, this paper uses XGBoost machine algorithm, InVEST and PLUS model to extract ecological source from the trade-off between ecosystem service value and ecosystem service importance at grid scale. Based on XGBoost, the spatial weight distribution of ecological resistance surface and key ecological elements are optimized, and the ecological security pattern of Chengdu-Chongqing urban agglomeration under multiple scenarios is identified and the optimization strategy is proposed. The results show that: (1) In 2020 and 2035 (NDS, CPS, EDS, EPS) the number of ecological source patches in Chengdu-Chongqing urban agglomeration is 53,51,50,43 and 51, respectively, and the area is 24892.75,24462.57,24119.43,23833.75 and 27249.36 km_², respectively. The ecological source patches are ‘U-shaped’ semi-enclosed structure in space and concentrated on the edge of Chengdu-Chongqing urban agglomeration; (2) In 2020 and 2035 (NDS, CPS, EDS, EPS), the number of ecological source patches in Chengdu-Chongqing urban agglomeration is 53,51,50,43 and 51, respectively. Under different development scenarios in 2020 and 2035, the ecological corridor of Chengdu-Chongqing urban agglomeration presents a network structure of ‘edge through-medium sparse-east dense’. The ecological pinch points and ecological obstacles are ‘dotted’ and concentrated in the parallel ridges and valleys of eastern Sichuan and the surrounding areas with the Chengdu Plain as the core. (3) Based on the identification of multi-scenario ecological security pattern, the ecological security optimization strategy of “one axis, two belts, four zones and multiple points” in Chengdu-Chongqing urban agglomeration is proposed from the perspective of “anti-planning”. One axis, through the east-west of the study area, the river source ecological protection axis based on the main stream of the Yangtze River, the south-north east-west axial belt based on the broken ecological source in the middle of the urban agglomeration and the main tributaries of the Yangtze River, the western and southwestern Sichuan ecological key barrier areas guaranteed by large-area continuous ecological source areas, the eastern and southern Sichuan ecological fragile conservation areas supported by ecological source areas and ecological pinch points, and the central part of the urban agglomeration. The research results can provide a scientific basis for the ecological security construction of Chengdu-Chongqing urban agglomeration.