A ventilation and air conditioning system, characterized in comprising: a ventilation and air conditioning body comprising a ventilation component and a heat exchanging component arranged in a common housing and separated by a partition board , wherein the ventilation component has a ventilation outlet , and the heat exchanging component has a heat exchanging inlet and a heat exchanging outlet , wherein the ventilation and air conditioning system comprises an automatic air-output device arranged at the ventilation outlet , the automatic air-output device being configured to open or close the ventilation outlet according to an operating state of the ventilation component ; a ventilation inlet of the ventilation component is in communication with a purification chamber through an air inlet duct , and an end of the purification chamber away from the air inlet duct is provided with the ventilation outlet ; the purification chamber is provided with a filter screen therein, a first blower is provided between the filter screen and the ventilation outlet , and the first blower is arranged adjacent to the ventilation outlet ; a heat exchanging unit is provided between the heat exchanging inlet and the heat exchanging outlet of the heat exchanging component , the heat exchanging unit has a U-shaped structure, an open end of the U-shaped structure faces downward and is provided with a second blower that is arranged adjacent to the heat exchanging outlet ; and the heat exchanging outlet is configured for the air inlet duct to pass through and extend through the housing, and extend to an exterior of a side of the housing away from the ventilation component . a ventilation and air conditioning body comprising a ventilation component and a heat exchanging component arranged in a common housing and separated by a partition board , wherein the ventilation component has a ventilation outlet , and the heat exchanging component has a heat exchanging inlet and a heat exchanging outlet , wherein the ventilation and air conditioning system comprises an automatic air-output device arranged at the ventilation outlet , the automatic air-output device being configured to open or close the ventilation outlet according to an operating state of the ventilation component ; a ventilation inlet of the ventilation component is in communication with a purification chamber through an air inlet duct , and an end of the purification chamber away from the air inlet duct is provided with the ventilation outlet ; the purification chamber is provided with a filter screen therein, a first blower is provided between the filter screen and the ventilation outlet , and the first blower is arranged adjacent to the ventilation outlet ; a heat exchanging unit is provided between the heat exchanging inlet and the heat exchanging outlet of the heat exchanging component , the heat exchanging unit has a U-shaped structure, an open end of the U-shaped structure faces downward and is provided with a second blower that is arranged adjacent to the heat exchanging outlet ; and the heat exchanging outlet is configured for the air inlet duct to pass through and extend through the housing, and extend to an exterior of a side of the housing away from the ventilation component . <EOS>