Abstract: Objective The patient monitors were used to explore the alarm fatigue in a cardiac care unit and to investigate the awareness and reaction of nurse to alarms. Methods A semi-structured survey was taken to acquire nurses’ feeling and knowledge about monitoring alarm. Three full-time researchers were scheduled to track the alarms with annotations, and analyze the alarm data of 12 patient monitors using central monitoring system. Results A total of 72 310 unique alarms occurred in the 67-day study period. About 75.7% of them were physiological alarms and less than 10% of medium-low alarms were false positives. The average alarm rate was 128 alarms/patient-day. Conclusion There remains alarm fatigue in CCU, the alarm accuracy has improved than the past by applying new technologies. In some cases, clinicians will pay more attention to trend alarm and combination alarm.