Objective: To explore the association of screening myopia and sitting posture habits as well as screen viewing distance among primary school students, providing a scientific basis for myopia prevention and intervention among primary school students. Methods: From April to June 2024, a convenient sampling method was used to enroll 1 394 fourth grade students from four primary schools in a district of Beijing for vision examinations and questionnaire surveys. Logistic regression models were employed to analyze the relationship of screening myopia detection and sitting posture habits as well as viewing distance. Results: The screening myopia prevalence among primary school students was 63.8%. About 13.1% of students self reported poor sitting posture, and 47.1% selfreported a viewing distance of ≤20 cm. After adjusting for covariates including age, gender, school, sleep quality, parental myopia status, physical fitness level, daily high intensity physical activity, weekend outdoor activity time and types of after school services, Logistic regression analysis showed that students with poor sitting posture were more likely to have screening myopia than those with normal sitting posture ( OR =1.73,95% CI =1.03-2.92); students with a viewing distance of ≤20 cm were more likely to have screening myopia than those with a viewing distance of >20 cm( OR =1.32, 95% CI =1.02-1.71)( P <0.05). The association between sitting posture and screening myopia was more significant among boys( OR =2.00, 95% CI =1.03-3.88, P < 0.05 ). A multiplicative interaction was observed between sitting posture and viewing distance. Compared to primary school students with normal posture and a viewing distance of >20 cm, those with poor posture and a viewing distance of >20 cm were more likely to have screening myopia ( OR =1.82, 95% CI =1.12-2.96， P <0.05). Conclusions Both sitting posture habits and screen viewing distance are related to screening myopia in primary school students. Poor sitting posture poses a higher risk than screen distance, and the two factors exhibit an interactive effect on myopia risk.