The invention provides an internal liquid leakage monitoring system of a nuclear power exciter air cooler, comprising a leaking liquid collecting groove, a leaking liquid drainage groove, a leaking liquid collecting pipe and a leaking liquid monitoring device. The leaking liquid collecting groove is disposed at the air pipe in the air cooler. The leaking liquid drainage groove is connected to theleaking liquid collecting groove. One end of the leaking liquid collecting groove is connected to the leaking liquid drainage groove, and the other end of the leaking liquid collecting groove is connected to the leaking liquid monitoring device. The internal liquid leakage monitoring system of a nuclear power exciter air cooler is advantageous in that through the sealing, drainage, collecting andmonitoring of the leaking liquid in the exciter air cooler, the monitoring and prevention of liquid leakage in the exciter air cooler can be realized, the short circuit and burnout of the exciter caused by the liquid leakage in the air cooler can be removed, and the safety hidden trouble of great accident caused by the liquid leakage in the air cooler can be prevented.