Abstract: Mechanical response, damage evolution, and surrounding-rock stability of coal-bearing sandstone under long-term low-temperature thermal cycling are investigated for closed-mine geothermal utilization. A combined experimental scheme of single low-temperature heat treatment and low-temperature thermal cycling is adopted. Uniaxial compression, acoustic emission (AE), three-dimensional digital image correlation (3D-DIC), and scanning electron microscopy (SEM) tests are performed. For single low-temperature heat treatment, seven temperature levels are set at 20, 40, 60, 80, 100, 140, and 180 ℃. For low-temperature thermal cycling, four cycling intervals, namely 20−40 ℃, 20−60 ℃, 20−80 ℃, and 20−100 ℃, are designed, with cycle numbers of 10, 30, 60, and 100. Effects of temperature level and cycle number on the macroscopic mechanical properties, deformation localization, and microstructural evolution of coal-bearing sandstone are analyzed. The results show that, under single low-temperature heat treatment, the response of coal-bearing sandstone is dominated by water escape, closure of primary microcracks, and improvement of particle contacts. At 180 ℃, the mass loss rate is only 0.412%, the wave velocity loss rate remains generally negative, and the compressive strength increases with increasing temperature, indicating densification strengthening and a negative damage effect at the initial stage of low-temperature thermal disturbance. Under thermal cycling, the strength evolution of coal-bearing sandstone exhibits clear stage-dependent characteristics. At low cycle numbers, a strengthening effect is still maintained, and the compressive strength after 10 cycles ranges from 71.53 to 84.87 MPa. As the cycle number increases, thermal fatigue damage gradually becomes dominant. After 100 cycles, the compressive strength decreases to 60.30−65.93 MPa, and deterioration becomes more pronounced under cycling with a larger temperature difference. The loss rates of wave velocity, elastic modulus, and compressive strength indicate that temperature controls the intensity of thermal damage development, whereas cycle number determines the degree of damage accumulation. Their coupled effect drives the transition of coal-bearing sandstone from initial strengthening to continuous deterioration. AE results show that, with increasing thermal cycling intensity, concentrated bursts of high-amplitude signals are weakened, sustained activity of low-amplitude signals becomes more evident, and the dominant-frequency distribution shifts from high-frequency dominance to an increased proportion of low-frequency signals. The 3D-DIC and AE location results indicate that strain concentration zones appear earlier and expand from a single localized region to multiple dispersed regions, while crack propagation changes from a simple through-going pattern to the coordinated development of multiple cracks. SEM observations show that the microstructure of coal-bearing sandstone successively undergoes densification, interfacial debonding, localized crack propagation, and enhanced crack connectivity. The microscopic damage is mainly controlled by thermal expansion mismatch among mineral particles and cyclic relaxation deterioration of cemented interfaces. Based on the macroscopic mechanical response, AE activity, deformation field, and microstructural characteristics, the damage evolution of coal-bearing sandstone under low-temperature thermal cycling is divided into four stages: negative damage, damage initiation, damage localization, and damage instability. According to the stage-dependent deterioration characteristics, the long-term stability state of surrounding rock in closed-mine geothermal systems is classified into a stability-maintenance zone, cumulative-deterioration zone, failure-sensitive zone, and instability-failure zone. Engineering operation should follow the principles of prioritizing low temperature difference, controlling cycling intensity, implementing zoning-based monitoring, and applying dynamic regulation. For water-bearing closed-mine environments, additional strength reduction caused by water-rock interaction and hydro-thermal coupling should also be considered.