Abstract： Objective To observe refraction changes in the flying cadets with subnormal distant vision by one year follow-up study in the flying school and to provide objective references to flying cadet selection. Methods One hundred and thirty-seven pilot cadets,whose eyes (172 eyes) were diagnosed as subnormal distant vision (0.8≤distant vision＜1.0),were selected as study group.Another 134 pilot cadets (268 eyes),who had the distance vision above or equal to 1.0,were taken as control group by the random selection from same school.Both groups were checked refraction by automatic refractor before and after mydriasis with Tropicamide. Results ① There was statistical difference on ametropia composing between groups in recruitment examination (x2= 79.925,P＜0.01).But one year follow-up study showed that the rate of ametropia before mydriasis had no significant difference between two groups (x2 =1.990,P＞0.05).Mixed astigmatism was newly found in both groups and obvious increased nearsightedness and decreased hyperopia cases were respectively observed.The refraction changes after mydriasis showed opposite variation comparing to the state of no mydriasis applied.Comparing with therecruitment examination,the nearsightedness decreased in study group but increased in control group one year later.The ametropia composing between groups had significant difference (x2 =9.366,P＜0.05).② Mydriasis resulted in the rate of myopia ametropia significantly decreased in both groups while hyperopia ametropia showed significantly increased tendency in both groups. ③ There is no significant difference on the superstandard ametropia,which mainly indicated myopia and then the astigmatism,between groups before mydriasis (x2=3.287,0.332,P＞0.05). Conclusions ① The subnormal distant vision of pilot cadets shows moderate improvement based on one year fellow-up study.The rate of ametropia has no significant difference between two groups beforemydriasis.② The refraction degree of control group expresses more fluctuation.Itis possible due to the reason of high rate of distant vision.③ Nearsightedness would be the main reason of causing superstandard ametropia.