The urban ecological security pattern is a vital spatial framework for maintaining ecosystem health and achieving sustainable development. Using Guiyang, a vulnerable mountainous city, as a case study, this research integrated multiple methods, including the remote sensing ecological index (RSEI), habitat quality assessment, ecological importance evaluation, morphological spatial pattern analysis (MSPA), and data on ecological protection zones and natural protected areas, to identify ecological sources. The minimum cumulative resistance (MCR) model and circuit theory were utilized to construct the ecological security pattern. The findings are as follows: 1) A total of 33 ecological sources were identified in Guiyang, covering 2, 448.20 km², primarily located in the northern region, including 16 primary and 17 secondary sources; 2) 84 ecological corridors were delineated, comprising 30 primary corridors, 50 secondary corridors, and 4 potential corridors, forming a spatial distribution along the central longitudinal axis; 3) Key ecological pinch points (52), barriers (57), and fracture points (53) were identified, emphasizing critical areas for ecological protection and restoration; 4) A "one axis, two belts, and multiple nodes" ecological security framework was developed, providing a scientific foundation for optimizing Guiyang's ecological space and guiding ecological restoration. This study offers valuable insights for the optimization of ecological security patterns in mountainous cities.