ObjectiveTo investigate the prevalence of nonalcoholic fatty liver disease (NAFLD) in Haikou, China and the association of NAFLD with metabolic syndrome (MS) and its components. MethodsA total of 18771 persons who underwent physical examination in Haikou People’s Hospital from September 2016 to August 2017 were enrolled. Body height, body weight, blood pressure, fasting plasma glucose, blood lipids, and liver function parameters were measured, and ultrasound examination was performed for the liver. The prevalence rate of NAFLD was calculated, and the association of NAFLD with MS and its components was analyzed. The t-test was used for comparison of continuous data between groups, and the chi-square test was used for comparison of categorical data between groups. ResultsOf all 18771 persons, 5715 had NAFLD, resulting in a prevalence rate of 30.45%; the prevalence rate of NAFLD was 41.74% in men and 1722% in women. Men aged 45-59 years had the highest prevalence rate of NAFLD, and women aged ≥45 years had the highest prevalence rate. Men had a significantly higher prevalence rate of moderate NAFLD than women (8.10% vs 1.19%, χ2=476.1, P＜0.001). Men with obesity and overweight had a higher prevalence rate of NAFLD, and women with obesity had a higher prevalence rate; in both men and women, there was a significant difference in the prevalence rate of NAFLD between groups with different levels of body mass index (BMI) (χ2=2111，1917，all P＜0.001). NAFLD patients had significantly higher BMI, blood pressure, fasting plasma glucose, triglyceride, alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transpeptidase than non-NAFLD patients (t=41.276, 32.339, 31.487, 12.185, 9.716, 38.382, 26.350, 25.291, and 15.008, all P＜0.001). ConclusionThere is a high prevalence rate of NAFLD in people undergoing physical examination in Haikou, and men tend to have a higher prevalence rate than women. NAFLD is closely associated with MS and its components.