Abstract： Objective To investigate changes in the mental health status of pelagic fishermen during prolonged voyage,so as to provide solid evidence for further comprehensive investigation and development of mental health protection measures.Methods SCL-90 symptom checklist,sRSS sleep questionnaire,the revised version of MBI-GS burnout inventory by Professor Li Chaoping and Coping style scale were used to perform a repeated cross-sectional group questionnaire survey and analysis in pelagic fishermen,3 days before sailing,at month 3 and month 6 during voyage,and at day7 after voyage.The obtained data were compared with those of the Chinese norms and statistical analysis was also made in the study.Results There was no statistical significance in the scores of SCL-90 scales 3 days before sailing,as compared with those of the Chinese adult norms (P ＞0.05).However,at month 3 after prolonged voyage,the mental health status of the pelagic fishermen as a whole was significantly decreased.Total average scores of the 10 factors and SCL-90 were significantly higher than those of the data detected 3 days before sailing and at day 7 after sailing (P ＜0.01).Furthermore,the data detected at month 6 were further increased,as compared with those detected at month 3 (P ＜ 0.05).In addition,such data as sleep time,sleep quality,lack of awakening,lack of sleep,difficulty in falling asleep,sleep instability,nightmare and night terror,medication and total sleep scores of the pelagic fishermen were all significantly lower than those of the Chinese norms and the oceangoing seafarers,and statistical significance could be noticed when comparisons were made between them (P ＜ 0.05 or P ＜ 0.01) Three months after voyage,the 3 dimensional scores of the burnout inventory and burnout comprehensive scores in the pelagic fishermen were all significantly higher than those 3 days before sailing and at day 7 after sailing (P ＜ 0.01).Furthermore,the burnout scores detected at month 6 were higher than those detected at month 3,also with statistical significance (P ＜ 0.05).In the 14 coping styles,the percentage of relief only through the access of smoking and alcoholism in the pelagic fishermen was higher than that of the Chinese norms.However,the scores of other coping styles were all lower than those of the Chinese norms,also with statistical significance (P ＜ 0.01).Conclusions The mental status of the pelagic fishermen obviously got lower after 3 months of prolonged voyage,and it would further worsen at month 6.The mental health status of the pelagic fishermen during prolonged voyage was poor,which relevant administrative departments should pay special attention to.