Objective To investigate the prevalence of myopia among 3~6 year old preschool children in Haidian District,Beijing and analyze its influencing factors.Design Cross-sectional study.Participants 1864 preschool children from 27 kindergartens in Haid-ian District,Beijing.Methods The visual acuity and diopter of the children were tested using LogMAR visual acuity chart and comput-er optometer which test after cycloplegia with 1.0%cyclopentate hydrochloride.Daily outdoor activity time,daily use time of electronic products,daily total sleep time,reading and writing posture,picky eating,and abnormal eye performance and parents'myopia were col-lected by questionnaire.Myopia is defined as equivalent spherical ≤-0.50 D.Multivariate logistic regression analysis was used to ana-lyze the influencing factors of myopia.Main Outcome Measures myopia prevalence,risk factors.Results The prevalence of myopia was 4.61%in the 1864 preschoolers,in which,5.35%in boys and 3.81%in girls(P>0.05).Multivariate analysis showed that at least one parent myopia(OR=1.60,P<0.05),daily outdoor activity time<2 hours(OR=0.03,P<0.05),daily use of electronic products(OR=1.07,P<0.05),daily sleep time less than 10 hours(OR=1.89,P<0.05)and abnormal eye appearance(OR=1.34,P<0.01)were positively cor-related with the prevalence of myopia.Conclusion The prevalence of myopia among preschool children in Beijing Haidian District is about 4.6%.Appropriately increasing outdoor activity time,ensuring sufficient sleep,controlling the use of electronic devices,showing abnormal eye symptoms,and paying more attention to children whose parents have a history of myopia can help prevent and control my-opia in preschool children.(Ophthalmol CHN,2024,33:362-366)