Established an indirect contact thermocline single tank heat storage two-dimensional mathematical model, its thermal energy storage properties has been studied. Using Fluent software to perform CFD simulations on tubular accumulator, the thermal storage medium used for the model was sand, heat transfer fluid was air, two types of media were separated by a stainless steel tube in the middle. The simulation results agreed well with the existing small-scale test bed regenerative results. The results showed that for a 6m long heat storage tank, when the flow rate changes in the range of 4,6,8 m/s, the heat storage efficiency was 0.708, 0.534, 0.425,respectively. High flow rates, temperature distribution inside the tank tends to uniform, which is not conducive to the formation of thermocline.