The present disclosure relates to a system and a method for discharging carbon monoxide (CO) by using a CO leakage alarm device and, more specifically, to a system and a method for discharging CO by using a CO leakage alarm device, the system and the method being operated on the basis of the Internet of things (IoT) so as to: detect CO leakage caused by damage to a boiler flue and sound an alarm through at least two from among the CO leakage alarm device, a boiler controller, a wall pad, and the like, automatically perform boiler ventilation and indoor air ventilation when the leakage is determined; and directly notify CO leakage-related authorities and users about the CO leakage.