Based on the deficiencies of existing ground heat exchangers, a new type energy-storage heat exchanger is proposed, which consists of three inlet pipes and one thermal insulation outlet pipe. Thermal resistance of this new type heat exchanger is calculated, which shows a much smaller value over conventional ones. Experimental measurements to evaluate the performance of single-U, double-U and the new design, were carried out in boreholes about 96 meters deep, which showed superior performance of the new type. The thermal resistance of the new type was 29%-34% and 10%-15% smaller than that of single-U and double-U respectively. The circulation water temperature rise of new type was 1.5 ℃ lower than double-U.