To improve the operating efficiency of advanced adiabatic compressed air energy storage (AA-CAES) systems under wide-load peak-regulation conditions, this paper focuses on the problem that a fixed reheating temperature setting is difficult to adapt to part-load operation in a pressurized-water AA-CAES system. The influence of reheating temperature on the system electricity-to-electricity efficiency is investigated. A dynamic system model is established based on the APROS platform. The effects of reheating temperature on air flow rate, turbine efficiency, auxiliary power consumption, and system efficiency under different loads are analyzed. The results indicate that the optimal reheating temperature has obvious load dependence. Under high-load conditions, the enthalpy gain caused by reheating is dominant, and a higher reheating temperature is beneficial to improving system efficiency. Under deep part-load conditions, increasing the reheating temperature reduces the required air mass flow rate, makes the turbine deviate from the high-efficiency region, and increases the proportion of auxiliary power consumption of the constant-pressure heater. As a result, the benefit of high-temperature reheating is weakened and may even become an efficiency penalty. Therefore, a load-adaptive reheating temperature regulation strategy is proposed in this paper, which can provide a reference for thermal management optimization of pressurized-water AA-CAES systems during wide-load operation and deep peak regulation.