The experimental system of the tank with heat-exchanger coil was built to investigate the influence of immersed heat exchange coil position inside a storage tank on the heat charging and discharging performance of the tank. The coil convection transient Nusselt number and the discharging efficiency were introduced to analyze the influence of the coil position on the discharging performance of the tank and the charging efficiency during heat charging process. The experiment result indicated that the performance of the coil transient convection and the discharging efficiency increased with the rising of the coil position. When the flow rate was 5L/min, the coil convection transient Nusselt number of the tanks with the middle-coil and the top-coil were higher 25.1% and 73.1% than the bottom-coil tank, respectively. While the discharging efficiency of the tanks with top-coil was higher 5% and 13.1% than that of the middle-coil tank and bottom-coil tank respectively. The gap of the discharging efficiency in the tank with different position coils reduced with the increasing of the flow rate. The charging efficiency reduced with the rising of the coil position.