Abstract: Objective To investigate the prevalence of myopia among 4-6 years old children in Longhua District, Shenzhen and analyze the factors in relation to it so as to provide suggestion for the prevention and control of myopia among preschool children.Methods A cross-sectional survey and myopia screening were conducted to analyze factors related to myopia among all senior kindergarten children at Longhua District, Shenzhen in 2019.Results A total of 23 007 children were recruited. Of which 95 children were myopia, and the prevalence rate was 0. 41%. Prevalence of myopia among male children and female children was 0. 50% and 0. 31% respectively(χ²= 5. 305, P= 0. 021). With regard to screen exposure time in infants and toddlers, the longer the daily exposure, the higher the myopia prevalence rate among 0-1 and 1-2 years old group. Prevalence of myopia was 0. 35% and 0. 37% in these 2 groups with screen exposure time ＜ 0. 5 h/d, which was much lower than that of other groups with screen exposure time≥0. 5 h/d(0. 67%-0. 98%, 0. 59%-0. 72%). The differences were statistically significant(P＜ 0. 05). There was no difference in terms of prevalence of myopia among different groups with different screen exposure time among 2-5 years old children(P＞0. 05).ConclusionMyopia of preschool children should be paid more attention. Advocacy related to myopia prevention and control of screen exposure time should be strengthened in order to prevent bad custom of visual behavior for younger children(especially boys).