Objective To characterize the distribution of conjunctival sac flora and antibiotic susceptibility in healthy people of different ages.Methods Totally 1 839 conjunctival sac secretion samples from 1 131 people without infectious eye diseases attending Qingdao Eye Hospital of Shandong First Medical University from 2018 to 2021 were retrospectively analyzed.These people were divided into four groups according to age:children(≤18 years old),young(19-45 years old),middle-aged(46-65 years old),and elderly(＞65 years old).Differences in the distribution of conjunctival sac flo-ra and antibiotic susceptibility among these groups were compared using the chi-square test or Fisher's exact test.The Bonferroni method was used for pairwise comparisons.Results The total bacterial detection rate of the conjunctival sac in the study population aged 1 month to 91 years old(median:11.00 years old;quartiles:5.00 years old,40.00 years old)was 64.93％;the bacterial detection rate in the children group(76.79％)was significantly higher than that in the young,middle-aged and elderly groups(all P＜0.001).Staphylococcus epidermidis(55.97％),Staphylococcus aureus(8.60％)and Streptococcus mitis(7.52％)were the most common bacteria in the conjunctival sacs.Gram-positive bacteria were re-sistant to most penicillins(16.79％-53.47％)and macrolides(17.21％-20.87％)antibiotics,and highly susceptive to van-comycin(99.56％)and gatifloxacin(98.57％).Gram-negative bacteria had low susceptibility rates to cephalosporin(41.38％-80.00％)antibiotics and were susceptive to amikacin(90.48％)and fluoroquinolone(90.91％-97.73％)antibi-otics.Of the common antibiotics used in ophthalmology,the susceptibility rate of fusidic acid was the worst in the children group(54.55％),which was significantly lower than the other three groups(all P＜0.001).Gatifloxacin had a susceptibili-ty rate of more than 90％in different Gram-stained bacteria in all groups,with an overall sensitivity rate of 98.44％.Con-clusion Staphylococcus epidermidis is the most common bacteria in the conjunctival sac in healthy people of all ages.Gatifloxacin is generally susceptive in different Gram-stained bacteria in people at different ages,and may be considered as the first choice for perioperative empiric antibiotics in ophthalmology.