Abstract: In order to promote operation characteristics of the cold end of an indirect air-cooled power generating unit and achieve both quality and efficiency improvements for the unit, a novel indirect air-cooled system is proposed in this paper. A phase-change heat storage tank filled with material RT35HC is connected in series with the dry cooling tower and the condenser to realize the "peak-shifting and valley-filling" of waste heat emission of the unit. Taking a 600MW supercritical indirect air-cooled unit as an example, thermodynamic models of the steam-water cycle and the novel indirect air-cooled system are separately established and then coupled for iterative computations, allowing thermal characteristics of the unit to be analyzed and thermo-economic evaluations to be performed under various operating conditions. The results show that it is a reliable integration method of connecting the phase-change heat storage tank in series downstream of the dry cooling tower. In this way, part of waste heat of the unit can be absorbed by the tank to relieve cooling pressure on the dry cooling tower under high ambient temperature and high unit load, and the stored heat can be discharged through the dry cooling tower to the environment under low ambient temperature and low unit load. Considering a complete cycle of 2.5h heat release and 1.05h heat storage, a heat capacity of 253MW·h for the tank requires a heat exchange area of 5996m². With this configuration, the unit saves roughly 5t of standard coal during one complete cycle, which translates to a reduction in standard coal consumption rate of 3.60g/(kW·h). Besides, the fluctuation in unit backpressure is diminished by 7kPa. The case study confirms that the integration of heat storage tank to the cold end of an indirect air-cooled unit is beneficial to operating economy of the unit, and it helps to reduce the wide fluctuations of thermal parameters as well.