The invention discloses a carbon monoxide poisoning preventive control system for an idling automobile, which comprises a carbon monoxide concentration detection unit, an interior personnel infrared detection unit, a signal processing unit, a first relay, a second relay, a third relay, a fourth relay, an alarm lamp, a buzzer, an automobile horn switch, a window ascending button, a window descending button and an automobile ignition switch. The carbon monoxide concentration detection unit and the interior personnel infrared detection unit are connected with the signal processing unit through wires, and the signal processing unit is connected with the alarm lamp and the buzzer through wires and further connected with a signal source port of each of the first relay, the second relay, the third relay and the fourth relay through a wire. Two wiring ports of a normally-open switch of each of the first relay, the second relay, the third relay and the fourth relay are in parallel connection with the automobile horn switch, the window ascending button and the window descending button through wires, and the two wiring ports of the normally-open switch of the fourth relay are serially connected with the automobile ignition switch through a wire.