Abstract: The radar cabin, with a lot of electronic equipment in it, is characterized by abnormal internal structure, small and relatively closed space. If human thermal comfort is not good, the operator in it for a long time will suffer from fatigue, trance, irritability, etc., and thus the reliability of personnel operation is reduced. The air conditioning system is the main equipment for environmental control in the cabin. On the premise of determining the type of air conditioner, the wind speed at the air outlet and the wind resistance of air-duct are focused on from human thermal comfort. The type & layout of air-duct and the number of air outlets are determined by combination numerical simulation and field tests. The results show that the temperature distribution in the cabin is uniform, the wind speed at the air outlet is reasonable and the thermal comfort is significantly improved with this method.