Abstract: Aiming at the application of thermal storage technology in peaking of the combined heat and power（CHP） plants, a water single-tank thermocline thermal energy storage（TES） experimental system was designed. Combined with the experimental results, a physical mathematical model of single-tank thermocline TES that can investigate simultaneous charge and discharge process was established. The numerical approach was verified by the corresponding single charge experiment. To discuss the TES performance of the single-tank thermocline TES system, the process including discharge, dissipation, cyclic operation and simultaneous charge and discharge were investigated by numerical simulation. The results indicate that the discharge efficiency of the high temperature is slightly higher than that of the low temperature under the condition of the same cut-off temperature factor and actual heat output. Under the influence of the initial position and thickness of thermocline, the relative growth rate and the growth rate of the thermocline varies during the dissipation. Combined with the practical application of the TES system in CHP, the temperature distribution inside the tank during the simultaneous charge and discharge process was presented. During the cyclic operation, as the number of cycles increases, the thermocline thickness increases continuously. And the effective utilization rate of the thermal storage tank is continuously reduced. The research results have guiding significance for the application of water single-tank thermocline TES in the CHP plants.