BACKGROUND Chaotic monitor alarm management generates a large number of alarms, which result in alarm fatigue. Intensive care unit (ICU) nurses are caretakers of critically ill patients, the effect of alarm management affect patient safety directly. OBJECTIVE To evaluate the effect of monitor alarm management training based on the theory of planned behaviour for reducing alarm fatigue in intensive care unit nurses. METHODS A randomised, single-blind trial. This article follows the requirements of CONSORT statement. METHODS The study was conducted from February 2019-May 2019 in a tertiary A-level hospital. 93 ICU clinical nurses were included, and they were randomly assigned into two groups. METHODS Nurses in the experimental group (n = 47) received a 12-week alarm management training course based on the theory of planned behaviour. Nurses in the control group (n = 46) received regular training. All nurses' alarm fatigue scores were measured with a questionnaire before and after the study period. Total number of alarms, nonactionable alarms and true crisis alarms were recorded continuously throughout the study period. RESULTS For baseline comparisons, no significant differences were found. By the analysis of independent samples one-way ANCOVAs, the nurses' adjusted alarm fatigue scores at the post-test in the experimental group were significantly lower than those in the control group (p < .001). After the study period, adjusted total number of alarms and nonactionable alarms recorded in the experimental group were both significantly lower than those recorded in the control group (p < .001). After the study period, no significant difference between the two groups was noted in the adjusted number of true crisis alarms (p > .05). The interventions did not cause adverse events in either group of patients and did not cause adverse events in patients. CONCLUSIONS Intensive care unit nurses' alarm fatigue was effectively decreased by the monitor alarm management training based on the theory of planned behaviour. CONCLUSIONS (1) Monitor alarm training based on the theory of planned behaviour is effective in reducing nonactionable alarms and lowering alarm fatigue in ICU nurses. (2) The intervention considering the social psychological aspects of behaviour is effective in rebuilding the nurses' awareness and behaviour of alarm management. (3) Nurses are the direct users of monitoring technology. Hospital administrators should attach importance to the role of nurses in the medical monitoring system. We suggest that nursing managers implement training programmes in more ICUs in the future to improve alarm management ability and lower alarm fatigue in ICU nurses.