Abstract: Objective To investigate the prevalence of poor vision and family-related factors among primary students in Tianjin,and to provide evidence for effective prevention of poor vision.Methods A stratified cluster random sampling method was used to investigate 1 404 primary students from three primary schools in Tianjin.Standard logarithmic visual acuity chart was employed to examine studentss' eyesight,and a self-administrated questionnaire was conducted among students and parents to investigate the condition of primary school students' eyesight,and the data were analyzed by SPSS 22.0.Results The detection rate of students' poor vision was 43.1%,and the differences between different genders and different grades were of statistical significance (x2 =9.5,81.3,P<0.01).The only child(x2 =19.9),parental education levels(x2=20.5,32.4),parental eyesight(x2 =35.9),the location where child studies at home(x2=14.0),types of lamps and lanterns while studying(x2=21.3),turning on the night lights when the child sleeps(x2 =5.5),whether the parents focus on reading and writing habits of their children or not(x2 =6.9),whether the parents take their children outside to enjoy the sunshine or not (x2 =29.0) were associated with poor vision(P<0.05).Multivariate Logistic analysis indicated elder ages,female,genetic factor were independent risk factors for poor vision,whilst the variable that parents took the children outside to enjoy the sunniness was the protective factor(P<0.05).Conclusion The prevalence of poor vision among primary school students increased with the increase of grade.