The invention provides an environment-friendly air conditioner which comprises a housing, an air inlet, an air outlet, an air supply device and an air heat exchange device. The air conditioner has the improvements as follows: the air heat exchange device comprises an atomizing device, a water vapor atomizing chamber and an impounding reservoir; the water vapor atomizing chamber is provided with an air inlet port; the atomizing device is arranged in the water vapor atomizing chamber; the impounding reservoir is arranged at the lower part the water vapor atomizing chamber and communicated with the water vapor atomizing chamber; an air outlet port is formed at the lower part of the impounding reservoir and the water vapor atomizing chamber; the atomizing device is connected with one end of an underground heat exchanger through a pipeline; the impounding reservoir is connected with the other end of the underground heat exchanger through the pipeline; and the air heat exchange device and the underground heat exchanger form a water circulation passage. The air conditioner atomizes water which exchanges heat with geothermal resources, and then conducts heat exchange with indoor air, so as to achieve high efficiency of heat exchange and better cooling (heating) effects.