AIM: To investigate the behaviors of smartphone usage and parental knowledge of vision health among primary students in the rural areas of China. METHODS: In this school-based, cross-sectional study, a total of 52 606 parents of students from 30 primary schools in the Xingguo County were investigated through an online questionnaire from July 2020 to August 2020. The self-designed questionnaire contained three parts: the demographic factors of both children and parents, parental knowledge and attitude toward myopia, and the preventive treatment of myopia. RESULTS: A total of 52 485 appropriately answered questionnaires were received, showing an effective response rate of 95.1%. The average age of the primary students was 10.1±0.98y and the prevalence of myopia among the primary students was 40.3%. The age of myopia occurrence in elementary students was significantly correlated with the parents’ educational level (95%CI: 0.82-0.98, P=0.013), children’s gender (95%CI: 1.08-1.20, P<0.001), school location (county or countryside) (95%CI: 0.59-0.66, P<0.001), children’s smartphone ownership (95%CI: 1.09-1.26, P<0.001), and the average time spent on smartphone per day (95%CI: 0.78-0.88, P<0.001). School location in the county town, high family income, and high parents’ educational level significantly affected both parents’ myopia awareness and children’s vision-threatening behaviors (P<0.01). Left-behind children showed a higher incidence of vision-threatening habits than those who lived with their parents (P<0.01). CONCLUSION: The results reveal the current situation of myopia development among rural primary school students and their parents. This survey will serve as a guidance for designing myopic prevention policies in the rural areas of China.