ObjectiveTo determine the retinal thickness of normal children 3-6 years old and its relationship with the age and gender. MethodsIn a cross-sectional study, 480 eyes of 240 normal preschool children including 115 male and 125 female, ages 3 to 6 years in the urban of Beijing, China were included. The average age was (4.93±0.77) years old. The visual acuity, slit-lamp microscopy and frequency domain optical coherence tomography (FD-OCT, Optvue, Inc. USA) were examined. The retinal thickness of the macular fovea and 500, 750, 1500 μm from temporal and nasal side around the fovea were measured. 32 eyes were excluded from the study because they couldn't cooperate. Pearson correlation analysis was used to determine the correlation between age and macular retinal thickness. Independent samples group t-test was used to compare the differences between boys and girls. ResultsThe mean thickness of macular fovea was (169.10±20.587) μm. The mean macular thickness of boys was significantly higher than girls (t=-4.549, -6.167, -5.492, -5.163, -6.749, -7.494, -6.874; P≤0.001). The mean thickness of 500 μm and 750 μm from nasal side of macular fovea were significantly higher than temporal side (t=5.594, 15.778, 7.678, 18.180; P < 0.001). There was no significant relevance between macular thickness and age. ConclusionsThe mean macular thickness of boys is significantly higher than girls in normal children in the urban of Beijing. There is no significant relevance between macular thickness and age.