Objective To investigate the incidence and treatment effect of motion sickness of island-reef personnel during navigation, so as to provide data support for guiding the army to carry out motion sickness management, prevention and control. Methods A total of 132 island-reef garrison personnel with similar time on island, times to sea, taking warships, and sea conditions experienced and conditions of residence were selected. Basic information, severity and concomitant symptoms of seasickness, treatment history, eating and sleeping conditions were collected using questionnaires, and the factors associated with seasickness were analyzed. Results A total of 132 questionnaires were sent out and all were valid. Of the 132 respondents, 24 were females and 108 were males, and 6 (4.55%) had received vestibular function training to prevent seasickness before the navigation. Sixteen (12.12%) had no seasickness symptoms, 116 (87.88%) had seasickness symptoms, 91 (68.94%) had vomiting symptoms, and 90 (68.18%) accompanied by walking instability during the navigation. Totally 101 patients (76.52%) received treatment during seasickness, of which 38 (28.79%) were ineffective, 55 (41.67%) were partially relieved, and 8 (6.06%) were effective; while 31 (23.48%) did not receive any treatment. During the navigation, 34 (25.76%) could eat normally, while 98 (74.24%) could eat less or could not eat; 72 (54.55%) had normal sleep, while 60 (45.45%) had reduced sleep or insomnia. There was significant difference in the incidence of seasickness among respondents with different eating and sleeping conditions (all P<0.05), and incidence of seasickness was higher in respondents with reduced food intake or inability to eat, decreased sleep or insomnia. Conclusion There is a high incidence of seasickness among island-reef personnel during defense rotation navigation. Training for seasickness prevention should be strengthened before navigation, and drugs for sickness prevention, stomach protection and sleep aid should be given during navigation.