Objective: To observe the refractive status of preschool children, and to explore the prevalence and development trend of ametropia in preschool children, so as to provide support for controlling adolescent ametropia and improving children s health care service. Methods: This cross sectional survey was conducted among 27 561 preschool children (55 122 eyes) aged 3-6 years old in the High tech Zone of Suzhou from September to December 2020. The refractive status was screened by the US Weilun binocular optometry. Results: The total detection rate of ametropia was 9.5%, including 8.6% of astigmatism, 1.3% of hyperopia and 0.5% of myopia. The detection rates of myopia (1.1%) and hyperopia (2.2%) were the highest in the 6-year-old group, and the older the age was, the lower the spherical diopter was, and the higher the cylindrical diopter was. The abnormal rate of colposcopy in girls ( 1.3% ) was higher than that in boys (0.9%), and the abnormal rate of total anisometropia in women (2.3%) was also higher than that in men (1.9%). The main astigmatism was mixed astigmatism (49.1%) and compound hyperopia astigmatism (39.2%); The older the age, the lower the detection rate of compound hyperopia astigmatism. And it is dominated by regular astigmatism( 97.5% ); The higher the age, the higher the detection rate of astigmatism with the rule, while the lower the detection rates of astigmatism against the rule and oblique axis astigmatism. Conclusion The detection rate of myopia and hyperopia increased significantly at the age of 6, and anisometropia and axial astigmatism also reached the highest at the age of 6. Local health care departments should pay attention to children s astigmatism, especially astigmatism with the rule.