Introduction: The aim of this study was to explore the association between parental myopia and high myopia with children's refraction and ocular biometry in large-scale Chinese preschool children from the Beijing Hyperopia Reserve Study.Subjects/Methods: This cross-sectional kindergarten-based study enrolled children aged 3-6 years. Cycloplegic refraction, axial length (AL), and corneal radius (CR) were measured for all children. Parents were asked to complete a questionnaire about refractive status (no myopia, mild myopia <-3D, moderate myopia >=-3D and <=-6, and high myopia >-6D).Results: The study enrolled 2053 children (1069 boys and 984 girls), with a mean age of 4.26 +/- 0.96 years and mean spherical equivalent refraction (SER) of 1.11 +/- 0.97 diopter. Of the children, 90.7% had at least one myopic parent, and 511 children (24.9%) had at least one highly myopic parent. SER decreased significantly with increasing severity of parental myopia (P<0.001)). Preschool children's myopia was independently associated with parental myopia (OR, 10.4 and 11.5 for one and two highly myopic parent(s)). Age (OR=1.1), gender (OR=1.7; girls as references), near work time (OR=1.2), and both maternal (OR, 1.4 and 2.0 for moderate and high myopia) and paternal myopia (OR, 1.6 and 1.9 for moderate and high myopia) were independent risk factors for lacking hyperopia reserve.Conclusion: Severe parental myopia was associated with a lower SER, longer AL, and higher AL/CR ratio in preschool children. Parental myopia and near work may predispose children to faster elimination of hyperopia reserves before exposure to higher educational stress.