Objective To investigate the prevalence and related factors of irritable bowel syndrome (IBS) in a Chinese navy unit according to Rome Ⅲ classification and diagnostic criteria. Methods The questionnaire survey based on Rome Ⅲ criteria was conducted in 8600 officers and soldiers in Chinese naval force using multistage, stratified, cluster random sampling method. The difference was compared in influence of the criteria on the diagnosis of IBS between Rome Ⅲ and Rome Ⅲ criteria. Analyses were performed for related influencing factors. Results The incidence of IBS meeting Rome Ⅲ criteria was 15.91% (1205/7574), and higher in female than in male (20.37% vs 15.73%, P=0.009), and most of them were in the 41-45 year age bracket (34.6%). Defecation difficulty, abdominal pain/discomfort and abdominal bloating were the main symptoms. Drinking, frequent drug-taking, history of dysentery, family history, and feeling of fatigue might be the most important risk factors (P<0.01). The incidence of IBS based on Rome Ⅱ criteria was significantly lower than that of Rome Ⅲ (1.75% vs 15.91%, P=0.000). Conclusion The incidence of IBS in Chinese naval force is high, and it should be highly regarded. Rome Ⅲ process gives a higher incidence of IBS compared with Rome Ⅱ.