Objective To understand the prevalence of myopia and related risk factors among elementary school students in Mentougou District of Beijing. Methods A stratified cluster sampling method was used to select 3 882 elementary school students in the district for nakedeye vision testing, automatic computer optometry and questionnaire survey. Results The myopia rate of primary school students surveyed was 32.97%, and the myopia rate of girls was 34.80%, higher than that of boys (31.16%) (χ2=5.816, P=0.016). The myopia rate also increased with the grade (r=0.997,t=27.385, P0.001). Multivariate logistic regression analysis: the time used for doing homework more than 2 hours every day after school, time used in the computer for more than 2 hours a day, time used by teachers with the electronic screen for more than 15 minutes per class, reading a book or electronic screen under direct sunlight, time in watching TV or playing computer games without the limit of parents, and the break between classes in the teaching building were risk factors for myopia (OR=1.219, 95%CI:1.048-1.418; OR=1.489, 95% CI:1.066-2.097; OR=1.209, 95% CI:1.049-1.392; OR=2.316, 95% CI:1.639-3.271；OR=1.282, 95% CI:1.003-1.640；OR=1.206，95% CI:1.041-1.397). One of the parents was myopia and both parents were nearsighted, were risk factors for myopia (OR=1.558, 95% CI:1.270-1.911; OR=1.394, 95% CI:1.166-1.667; OR=2.058，95% CI:1.682-2.518).Conclusion The myopia rate of girls in elementary schools in Mentougou District of Beijing was higher than that of boys, and it increased with grades. The main risk factors related to myopia were long eye use time, time in watching TV or playing computer games without the limit of parents, improper use of eyes.