Amid the rapid progression of global climate change and the intensifi cation of human activities, the establishment of protected areas emerges as a fundamental strategy to mitigate biodiversity loss and ecosystem service degradation. Employing the mountainous regions surrounding the Sichuan Basin as the study area, this research assessed ecosystem service functions and examined ecological and environmental sensitivity to identify protection defi ciencies within existing protected areas. Subsequently, the Minimum Cumulative Resistance (MCR) model was used to identify potential ecological corridors and nodes, thereby facilitating the development of optimization strategies for the spatial confi guration of protected areas in the study region. The main results are as follows: (1) A method for assessing biodiversity was proposed. In the absence of continuous large-scale species distribution data, modifying the NPP indicator reduced dependence on a single vegetation index. (2) High-value areas for biodiversity maintenance, water conservation, and soil retention were identifi ed. The results indicate that only 17.55% of extremely important ecosystem service areas in the mountainous areas surrounding the Sichuan Basin are strictly protected, necessitating the establishment of new or expanded protected areas to fi ll protection gaps. (3) An ecological corridor system comprising 54 important ecological corridors and multiple nodes was constructed, identifying 13 critical ecological nodes and 52 general ecological nodes. (4) By adjusting protected areas and adding key ecological restoration zones, the protection ratio of extremely important areas in the mountainous areas surrounding the Sichuan Basin was increased to 29.18%, forming a multi-level protection network. This study aims to optimize the spatial pattern of ecosystems in the mountainous areas surrounding the Sichuan Basin, enhance connectivity among protected areas, and strengthen the ecological barrier in the upper Yangtze River region.