The invention is suitable for the technical field of wind tunnel experiments, and provides an icing wind tunnel heat exchanger outlet airflow temperature control system and method, and the system comprises a compressor, a condenser, a liquid storage tank, a refrigerant shield pump, a heat exchanger, a low-pressure circulation barrel, a controller, and an upper computer. An air suction pressure sensor is arranged at the air suction end of the compressor; an inlet and an outlet of the heat exchanger are respectively provided with a liquid inlet regulating valve and an air return regulating valve; a downstream air outlet of the heat exchanger is provided with a temperature sensor, and the temperature sensor and the heat exchanger are both arranged in the icing wind tunnel; the controller is in control connection with the compressor; the upper computer is connected with the temperature sensor, the return air regulating valve and the controller; the air suction pressure sensor is directly arranged at the air suction end of the compressor, the air suction pressure of the compressor can be visually and sensitively obtained, and the problems that in the prior art, due to the large volume of a low-pressure circulation barrel, the load increasing and decreasing speed of a refrigerating system unit is low, and finally the heat exchanger outlet airflow temperature has large hysteresis quality are solved.