SIGNIFICANCE Data regarding the epidemiology of reduced visual acuity (VA) among multiethnic children and adolescents in China are few. Understanding the vision-related health inequalities among different ethnic groups is crucial for health resource allocations and clinical managements for eye diseases. PURPOSE We aim to determine the prevalence, main causes, and health inequalities of reduced VA in multiethnic school students in rural China. METHODS A school-based eye survey including 7681 multiethnic school students aged 5 to 16 years in the southwestern part of China was conducted. Detailed ocular examinations including VA measurements, ocular motility evaluations, bilateral postcycloplegic refractions, and the assessments of the external eye, anterior segment, media, and retinal fundus were carried out by trained research vision professionals. Visual acuity was measured using a logarithm of the minimum angle of resolution E-chart, and reduced VA was defined as a presenting VA of worse than 20/40. Concentration index was initiatively utilized to measure health inequalities among different ethnic groups. RESULTS The prevalence of reduced VA was 11.4 per 100 children (95% confidence interval, 10.7 to 12.1%) based on the worse-seeing eye data. The prevalence of reduced VA increased with increasing age (P < .001 for trend) and was higher among girls compared with boys (P < .0001). Uncorrected refractive error was the principal cause for reduced VA, which accounted for 87.3% of the participants with reduced VA. The concentration index for reduced VA was 0.07 among different ethnic groups. CONCLUSIONS Compared with the estimates reported from previous studies on Chinese children and adolescents, a relatively lower prevalence of reduced VA was observed among multiethnic school students in rural China. Ethnic variations and health inequalities of reduced VA were not significant in this study.