AIM: To assess the prevalence of refractive errors in middle school students in Lanzhou city and explore the risk factors for myopia. · METHODS: A cross-sectional survey was conducted. A questionnaire assessed the students' socioeconomic background and visual tasks followed by visual acuity assessment and a full eye examination including slit-lamp examination, fundus evaluation, retinoscopy, and subjective refraction. · RESULTS: Among 2 256 enumerated students aged 15-19 years,2 037(90.3%) students had significant refractive errors. Myopia was the leading refractive error (1 951/2 256, 86.5%), astigmatism was the second most common refractive error (921/2 256, 40.8%), but amblyopia (10/2 256, 0.4%), strabismus (5/2 256, 0.2%), hyperopia (4/2 256, 0.2%) and other treatable eye disorders were uncommon. Almost 95.3% of students with significant refractive errors wore spectacles before the survey. Age, sex, visual tasks, and a parental history of myopia were risk factors for myopia. · CONCLUSION: The prevalence of refractive errors and the risk factors for myopia in schoolchildren in Lanzhou city are similar to those reported in other regions of China. Interventions of myopia progression should be performed to protect the visual acuity of school-aged students.