[Objective] The concrete lining structures of underground air storage caverns in compressed air energy storage (CAES) systems are subjected to the combined effects of periodic air pressure fluctuations and temperature variations during long-term operation. This study aims to systematically reveal the evolution of mechanical properties, the microscopic damage mechanisms, and the macroscopic constitutive behavior of concrete under synchronous temperature-pressure cyclic loading, establish a damage constitutive model that accurately describes its stress-strain response characteristics, and further clarify the synergistic deterioration effect of coupled temperature-pressure cyclic loading. [Methods] A method combining experimental investigation and theoretical modeling was adopted. First, based on the actual operational parameters of CAES caverns, coupled cyclic loading tests were conducted on C50 concrete cylindrical specimens to investigate the individual and combined effects of three key variables: the number of cycles, the upper limit of cyclic temperature, and the upper limit of cyclic stress. After cyclic loading, uniaxial compression tests and SEM observations were performed on the specimens to reveal the changes in macroscopic mechanical properties and the underlying microscopic mechanisms of concrete under such loading. Based on continuum damage mechanics and the equivalent strain principle, and using the Weibull statistical distribution to describe the distribution and evolution of micro-defects within concrete, a damage constitutive model was established. [Results] (1) Temperature-pressure synchronous cyclic loading significantly deteriorated the mechanical properties of concrete. Both the peak compressive strength and the secant elastic modulus of concrete decreased monotonically with the number of cycles, the upper limit of cyclic temperature, and the upper limit of cyclic stress. The most severe performance degradation occurred during the first 30 cycles, and the degradation rate gradually leveled off after 40 cycles. Particularly, the coupled temperature-pressure action produced a significant synergistic deterioration effect, where the combined effect exceeded the sum of individual effects. After 30 synchronous temperature-stress cycles, the peak strength of concrete decreased by approximately 22% compared to the uncycled reference group. In contrast, the same number of single-factor temperature cycles (without stress) or single-factor stress cycles (constant temperature of 25 ℃) resulted in strength reductions of only about 15% and -3%, respectively, with low-level stress cycling exhibiting a slight strengthening effect. This indicated that the synchronous alternating action of temperature and stress was not a simple superposition of independent effects but rather exacerbated the damage accumulation within concrete through mutually reinforcing mechanisms. (2) SEM observations indicated that the difference in thermal expansion coefficients between aggregates and cement mortar was the fundamental cause of thermally induced microcracks. The presence of periodic axial compressive stress generated additional stress at the tips of existing microcracks during the heating/pressurization phase, promoting their further propagation, and induced repeated shearing and friction on crack surfaces during the cooling/depressurization phase, exacerbating the degradation of interfacial bonding. This coupled thermo-mechanical process ultimately led to the accelerated accumulation and interconnection of damage in the interfacial transition zone (ITZ), the weakest link in concrete, which became the dominant mechanism for the sharp degradation of macroscopic mechanical properties. (3) The established damage constitutive model showed good agreement between the theoretically calculated stress-strain curves and the experimental curves under various working conditions. The model accurately reproduced the shape of the ascending branch, the location of the peak point, and the descending branch trend of the concrete stress-strain relationship after different cyclic histories. The damage evolution curves indicated that temperature-pressure synchronous cyclic loading not only significantly increased the initial damage value of concrete but also altered the development of damage during subsequent loading. Compared to reference concrete or concrete subjected only to temperature cycles, concrete that underwent coupled temperature-pressure cycles exhibited a faster development rate of the damage variable before reaching peak stress and a higher degree of damage at the peak stress point. This quantitatively confirmed the dual effects of “acceleration” and “aggravation” of the coupled temperature-pressure loading on the concrete damage process. [Conclusion] Through systematic experimental and theoretical analysis, this study comprehensively explains the performance degradation and damage evolution mechanisms of concrete under the coupled action of synchronous cyclic temperature-pressure loading. It clearly reveals the unique synergistic deterioration effects resulting from the coupling of temperature and stress fields. The established damage constitutive model provides a directly applicable constitutive relationship for nonlinear mechanical analysis and safety assessment of concrete structures in complex service environments such as CAES underground air storage caverns. The results confirm that the coupled effects of temperature-pressure cycles must be considered in the design and durability evaluation of such structures. Extrapolation based solely on single-factor test results may lead to a severe overestimation of the actual service life and safety margin of the structures.