Abstract: Aiming at the thermal environment of the non-airtight equipment cabin in an aircraft, TAITherm software was used to carry out steady-state temperature field analysis and transient temperature field analysis for the conditions of rest on the ground and medium-speed flight at different altitudes. Combined with the flight tasks of this type of aircraft, the thermal environment within the non-airtight cabin in the full flight envelope was repeatedly measured to explore and verify the change law of the thermal environment in the cabin. The results show that after the aircraft changes from low-altitude cruise to high-altitude cruise, the air node temperature in the cabin decreases continuously during the high-altitude cruise, and conversely, the air node temperature in the cabin increases continuously during the low-altitude cruise. During the climb of the aircraft, the air node temperature in the cabin rises first and then drops. In the descent stage of the aircraft, the air node temperature in the cabin drops first and then rises. During flight, the highest air node temperature in the cabin appears in the climbing stage, and the lowest temperature appears in the descent stage. The highest air node temperature in the cabin in the full flight envelope appears in the rest stage on the ground.