<p>The long-term stability of water-isolated coal pillars in water-accumulated goafs within ecologically fragile mining areas is severely threatened by the coupled effects of mine water immersion and mining disturbance. In this study, triaxial loading and triaxial loading with unilateral unloading experiments were conducted to simulate the complex stress paths experienced by water-isolated coal pillars throughout their service period. Based on the bearing deformation behavior and failure mechanisms of water-immersed coal samples, the main factors influencing the stability of water-isolated coal pillars during their service period were analyzed, and a comprehensive stability evaluation method was established. Acoustic emission (AE) monitoring results indicate that during triaxial loading, elevated moisture content and high confining pressure promote a transition in the failure mode of coal samples towards a tensile–shear composite pattern, whereas during triaxial loading with unilateral unloading, these factors facilitate a shift towards a predominantly tensile failure pattern. Under both stress paths, the stability of coal samples is affected by moisture content, confining pressure, and their inherent structure. Accordingly, the stability of water-isolated coal pillars is determined to be primarily influenced by three factors: the geomechanical environment of the surrounding rock, the structural characteristics of the water-isolated coal pillar, and anthropogenic mining activities. A multi-level fuzzy comprehensive evaluation system based on the analytic hierarchy process (AHP) was established, comprising these three primary indicators and thirteen secondary indicators. Indicator weights were determined using the scaling method and validated through consistency tests, and a membership function system integrating linear mapping and discrete assignment was constructed to quantify the fuzziness of influencing factors. Taking the 22614 working face of the Daliuta Coal Mine as the engineering background, the stability evaluation value of the water-isolated coal pillar was calculated to be 0.79, indicating an overall stable condition; however, the structural strength degradation under prolonged water immersion poses a potential leakage risk. Based on the evaluation results, a structural model incorporating an elastic zone and an inelastic zone was further established, from which the rational width of the water-isolated coal pillar was derived as no less than 34.12&#xa0;m, with a critical hydraulic head of 40.22&#xa0;m. The comprehensive qualitative and quantitative results suggest that it is necessary to enhance the monitoring of stress, seepage pressure, and deformation of the water-isolated coal pillar, so that effective prevention and control measures can be promptly implemented at potential local seepage points to ensure the safety and stability of the water-isolated coal pillar.</p>