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.