Objective：This study aims to study the risk factors of living habits and behaviors related to poor eyesight and refractive index in middle school students，so as to provide evidence for the prevention and control of myopia. Methods：A total of 1 430 students were investigated by cluster sampling from two schools in the district. Visual acuity and refractive examination and questionnaire survey were conducted. According to the results of visual acuity examination and computer optometry examination，the risk behaviors affecting poor visual acuity of middle school students in Xuhui district of Shanghai were analyzed. Results：The detection rate of visual acuity impairment in Xuhui district was 84.0%. Mild visual acuity impairment was 6.8%，moderate visual acuity impairment was 22.0%，and severe visual acuity impairment was 55.2%. The abnormal detection rate of refractive spherical mirror value was 82.7%，mild myopia was 48.0%，moderate myopia was 31.7%，and severe myopia was 3.0%. The detection rate of refraction（astigmatism） was 82.2%，including 51.2% low astigmatism and 31.0% high astigmatism. After chi-square test and logistic regression analysis，the influencing factors of visual acuity examination results were not completely consistent with the results of computerized optometry. After one-way factor analysis，lights in the classroom，parental myopia，gender，grade，sleep time，sweet drinks in a week，sitting time in a day，exercise time reduced，native place，eating egg per day，time of close eyes，reading with lamp，rest area，reading book or looking electronic screens in walking，and reading book or looking electronic screens in the sun are influence factors. After the multi-factor analysis，gender，grade，frequency of eating vegetables every day，classroom light，PE classes a week，parental myopia，native place，nationality，and the rest area are the influencing factors. Conclusion：There is poor visual acuity and high detection rate of ametropia among middle school students in Xuhui district of Shanghai，which may be influenced by their living habits.