【Objective】 To analyze the incidence and the factors correlated with subnormal vision of preschool children in urban areas of Lanzhou,and to provide evidences for the prevention and treatment of the subnormal vision. 【Methods】 A sample of 2 754 preschool children aged 3~6 years old from 10 kindergartens located in different functional urban areas of Lanzhou were selected randomly.4~6 years old children were examined by the standard logarithmic visual acuity chart.3 years old children were examined by symbols chart.Refrangibility was detected using Suresight hand-held refractometer and at the same time,the factors related with abnormal vision were studied. 【Results】 The prevalence of subnormal vision acuity in preschool children in Lanzhou was 13.9%.The subnormal rate decreased gradually as the age increasing.Among the 9 factors,four of birth weight,gestational age,the eyesight of the parents and daily sleep time were correlated with child subnormal vision. 【Conclusion】 Kindergartens and families should pay more attention to prompt children's good living habits of eye care.Meanwhile,public health education should also be enhanced among societies,families and kindergartens to take care of children's eye.