Objective To study the relationship of ocular biometric parameter and refraction in preschool children at age 3 to 6 years.Methods Retrospective case series of 103 children from kindergarten of Xuzhou were recruited.Each child had a dilated eye examination including macular thickness measured by Optical Coherence Tomography (OCT), axial length measurement using IOL-Master,and cycloplegic refraction.Macular thickness was presented with diameter for the central,inner,and outer macular regions being 1,3,and 6mm,respectively. Results Of the eligible children,89 children (86.40％) had high-quality data.The means of spherical equivalent refraction,central thickness,axial length and corneal refractive power were (+1.33±1.01)D,(189.01±25.49)μm,(21.98±0.71)mm,(43.52±1.56)D,respectively.The refraction showed significant difference among different age groups (F =3.23,P ＜0.05).There was negatively correlated between refraction and axial length(r =-0.46,P ＜0.01 ).Refraction was not significant correlation with macular thickness (r =0.02,P ＞0.05) and comeal refractive power (r =0.08,P ＞0.05).Conclusions A leptokurtic distributions of spherical equivalent refraction is presented in preschool children at age 3 to 6 years.Refraction is mainly affected by age,axial length.With the axial length and age increasing hyperopic refraction is decreasing.