A self-contained air conditioning system comprising a fresh air inlet, a return air inlet, an induced draft fan and an exhaust fan, a front-end air guide mechanism, a first heat exchanger, a second heat exchanger, a compressor, an expansion valve, a back-end air guide mechanism, an air supply outlet, and an air exhaust outlet, wherein an end of the air flow passage of the first heat exchanger and an end of the air flow passage of the second heat exchanger are respectively in communication with the air supply outlet and the air exhaust outlet through the back-end air guide mechanism; surfaces of the first heat exchanger and the second heat exchanger are coated with a material with a moisture absorbing function; a four-way valve is provided, wherein an outlet of the compressor is in communication with a first inlet of the four-way valve; a first outlet of the four-way valve is in communication with an inlet of the second heat exchanger; and an outlet of the second heat exchanger is in communication with an inlet of the first heat exchanger through the expansion valve; and an outlet of the first heat exchanger is in communication with a second inlet of the four-way valve; and a second outlet of the four-way valve is in communication with an inlet of the compressor; characterized in that: the surfaces coated with the material with the moisture absorbing function are inner surfaces of the air flow passages of the heat exchangers; the fresh air inlet and the return air inlet are in communication with an air mixing mechanism; the air mixing mechanism is in communication with another end of an air flow passage of the first heat exchanger and another end of an air flow passage of the second heat exchanger through the front-end air guide mechanism; the induced draft fan is disposed between the fresh air inlet and the air mixing mechanism; and the exhaust fan is disposed between the return air inlet and the air mixing mechanism; the induced draft fan is used to induce fresh air to the air mixing mechanism from the fresh air inlet; and the exhaust fan is used to suck return air to the air mixing mechanism from the return air inlet; the air mixing mechanism comprises a first upper inlet valve, a first lower inlet valve, a second upper inlet valve, a second lower inlet valve, an upper air mixing chamber, and a lower air mixing chamber; and the fresh air inlet is in communication with the upper air mixing chamber through the first upper inlet valve; the fresh air inlet is in communication with the lower air mixing chamber through the first lower inlet valve; the return air inlet is in communication with the upper air mixing chamber through the second upper inlet valve; and the return air inlet is in communication with the lower air mixing chamber through the second lower inlet valve. the surfaces coated with the material with the moisture absorbing function are inner surfaces of the air flow passages of the heat exchangers; the fresh air inlet and the return air inlet are in communication with an air mixing mechanism; the air mixing mechanism is in communication with another end of an air flow passage of the first heat exchanger and another end of an air flow passage of the second heat exchanger through the front-end air guide mechanism; the induced draft fan is disposed between the fresh air inlet and the air mixing mechanism; and the exhaust fan is disposed between the return air inlet and the air mixing mechanism; the induced draft fan is used to induce fresh air to the air mixing mechanism from the fresh air inlet; and the exhaust fan is used to suck return air to the air mixing mechanism from the return air inlet; the air mixing mechanism comprises a first upper inlet valve, a first lower inlet valve, a second upper inlet valve, a second lower inlet valve, an upper air mixing chamber, and a lower air mixing chamber; and the fresh air inlet is in communication with the upper air mixing chamber through the first upper inlet valve; the fresh air inlet is in communication with the lower air mixing chamber through the first lower inlet valve; the return air inlet is in communication with the upper air mixing chamber through the second upper inlet valve; and the return air inlet is in communication with the lower air mixing chamber through the second lower inlet valve.