Water to water heat pump system is a kind of high efficiency and energy-saving air-conditioning system which can not only supply heat but also cool by using shallow geothermal resources (also known as ground energy, including groundwater, soil or surface water). The system transfers the heat energy from low temperature to high temperature by inputting a small amount of electric energy. The ground energy is used as the heat source of heat pump heating in winter and the cold source of air conditioning in summer. The unit consumes 1kW of energy to obtain more than 4 ~ 5kW of cold / heat. The energy comes from underground energy, and the system does not emit any waste gas, waste water and slag to the outside. It is an ideal "green air conditioning" and can be widely used It is used in office building, hotel, school, dormitory, hospital, hotel, shopping mall, villa, residence and other fields.