To survey the refraction and binocular vision of preschool children in Jiangning-s Baijiahu district of Nanjing,and to analyze the distribution of refraction,the condition of ametropia and binocular vision. METHODS: Totally 1352 preschool children who had natural pupil in 7 kindergartens of Jiangnings Baijiahu district of Nanjing-were examined in the half-dark room by retinoscopy and-binocular vision instrument (type:TSJ-IV), including 728 boys and 624 girls. Refraction and binocular vision were statistically analyzed in different age groups.- RESULTS: The ratio of refraction error was 13.35%,which was the highest in 5-year-old group.There was no significant difference in those groups（P=0.408）. The proportion of astigmatism and hyperopia was significant difference in-3- year-old group,4- year-old group,5 -year-old group（P=0.003）,the ratio of astigmatism in 4-year-old group was significantly greater than that in other groups.162 children had binocular vision disorder,and the ratio of which was 12.01%,including 156 children (96.30%） with (range +6～+13°, ＞＋5°),and 6 children (3.70%） with exotropia(range -6～-12°,＞-5°)。There were significant difference in the ratio of binocular vision disorder in-three-groups,and the greatest in 3-year-age-group,mainly of esotropia（P=0.001）.-Among these 162 children with binocular vision disorder, there were 81.48%（132/162）cases with emmetropia. The ratio of refraction-error were no significant difference in-children with normal binocular vision and abnormal binocular vision（P=0.125）. CONCLUSION: Among preschool children in Jiangnings Baijiahu district of Nanjing, the main type of refraction error is astigmatism and hyperopia. Esotropia could be found in most abnormal binocular vision children. It is an useful method by retinoscopy and-binocular vision instrument with natural pupil in the half-dark room to survey refraction and primary binocular vision function of preschool children."