Objective: To explore the association of outdoor activity time and sleep duration with screening myopia in primary school students, so as to provide strategies for myopia prevention. Methods: Through a convenience sampling method, a survey was conducted among 4 248 primary school students aged 7-13 years from three primary schools in Xihu District, Nanchang City, Jiangxi Province from May to July, 2023. The average daily outdoor activity time and sleep duration on both weekdays and weekends were investigated in primary school students by using a self designed questionnaire. Uncorrected visual acuity tests and non cycloplegic autorefraction were measured by professional optometrists. Inter group comparisons were conducted using the Chi square test. Logistic regression model was used to analyze the association of outdoor activity time and sleep duration with screening myopia. Results: The detection rate of screening myopia in primary school students was 33.6%, with the rate in boys (32.0%) lower than that in girls (35.3%), and the difference was statistically significant ( χ 2=5.11, P =0.02). The analysis results of Logistic regression showed that after adjusting for factors such as gender, grade and parental education level, both average daily outdoor activity time ＜2 h on both weekdays and weekends ( OR =1.27, 95% CI =1.11-1.46) and sleep duration <10 h ( OR =1.17, 95% CI =1.01- 1.35 ), as well as their combined effect ( OR =1.57, 95% CI =1.25-1.98), were associated with an increased risk of screening myopia in primary school students(all P <0.05). Subgroup analysis results indicated that compared to boys ( OR =1.46, 95% CI = 1.07 -1.99), girls( OR =1.73, 95% CI =1.22-2.44) with insufficient outdoor activity time and sleep duration had a higher risk of screening myopia(both P <0.05). Conclusions There is a negative correlation of outdoor activity time and sleep duration with screening myopia in primary school students. Outdoor activity time and extending sleep duration should be increased to reduce the risk of myopia in primary school students.