A geothermal accumulator and a air-conditioning system using the geothermal accumulator, said geothermal accumulator includes a well pipe and a heat-accumulating pipe inserted within the well pipe coaxially, the lower portion and the upper portion of the well pipe are provided with inlet holes and outlet holes for underground water respectively, said heat-accumulating pipe is provided with a water-collecting chamber, a diffluent chamber, a heat-exchanging chamber and a water-accumulating chamber from the bottom up in sequence, the heat-exchanging chamber is provided with a plurality of axially disposed heat-exchanging pipes communicating with the diffluent chamber and water-accumulating chamber respectively, and a plurality of baffles attached to the outside of the heat-exchanging pipes, gap exists between the baffles and the heat-exchanging pipes, the upper portion of the heat-exchanging chamber is connected with a returning pipe, and the lower portion is connected with a discharging pipe, water inlet holes and drain holes are provided respectively in the side wall of the water-collecting chamber and the water-accumulating chamber. Said geothermal accumulator can be used in air conditioner system.