Ventilation rooftop air-conditioning system

A ventilation rooftop air-conditioning system, comprising:

• a housing unit comprising a main body, a lid body and a fixing element disposed in the main body to define a circulation channel and a ventilation channel, wherein the circulation channel has an air inlet, and the ventilation channel has an upper air vent and a lower air vent, wherein the upper air vent is opened or closed by means of the lid body;
• an air blower unit disposed between the upper vent and the lower air vent;
• and
• an air-conditioning unit which comprises an evaporator which is disposed on the fixing element, wherein the circulation channel is communicated to the ventilation channel through the evaporator;
• wherein the ventilation rooftop air-conditioning system has a ventilation mode in which air flows in the ventilation channel and does not pass through the evaporator and a circulation mode in which air passes through the circulation channel, the evaporator and the ventilation channel in turn.