In this paper,the performance of a single thermocline packed bed storage tank is analyzed,with hightemperature molten salt as the heat transfer fluid. Then,a theoretical model of the thermal storage system is established to reveal the law of thermal storage by means of numerical simulation. Moreover,the method to evaluate the performance of the thermal storage tank is put forward based on the capacity,the ability,the entropy generation,and the effectiveness,etc,and the effects of physical properties of different filler materials on the performance of the thermal storage system are analyzed. The results show that,under certain conditions of thermal storage,higher thermal conductivity are unfavourable to enhance the performance of the thermal storage tank,and that higher heat capacity per unit volume may result in better comprehensive thermal storage performance as well as high entropy generation.