A smart oronasal mask for a positive-airway-pressure device includes a mask body and a temperature sensor. The mask body has an air inlet and an air outlet. The temperature sensor is deposited in the mask body and located between the air inlet and the air outlet for sensing a temperature of a mixture formed by gas entering the mask body through the air inlet of the mask body and gas entering the mask body through the air outlet of the mask body. Then the positive airway pressure device adjusts air feed according to the temperature sensed by the temperature sensor in a real-time manner, so as to help keep a patient's respiratory tract clear.