Objective To observe the dynamic changes of oral microflora early colonized in infants.Methods The oral swab samples forthe studywere taken in 1day, 1, 3, 6, 9, 12 months after birth from 12 healthy neonates. By choosing suitable dilut- ed concentration, the samples were incubated aerobically, facultative anaerobically and anaerobically. The strains were identified by observing colony characteristics, Gram staining and biochemical tests.Results S.salivariuswas the most frequentmicroflora, followed byS.mitis,S.sanguis,S.gordoniiandS.mutansoccurred in oral cavity after tooth eruption.Veillonella spp. can be detected in oral cavity of 1-month-old babies,A.odontolyticuswas isolated from8.3% infants ofmore than 3 months old.L.aci- dophilusmaintained the lower prevalence in oral cavity of babies.Leptotrichia buccalisandCapnocytophaga spp. occurred in oral cavity of some dentate infants.Conclusion S.salivariusandS.mitisare predominant species in oral cavity of the infants,Veil- lonella spp. is the first and the most anaerobic species appeared in oral cavity of healthy babies.A.odontolyticusis the first actino- myces detected in oral cavity. With the increasing months, kind and amount of microflora increase dramatically.