Abstract: Objective: To explore the 16SrDNA method to determine the colonization of intestinal flora in the feces of newborns after birth and its clinical significance. Methods: Thirty newborns were selected as the research subjects.The stools of newborns were collected within 10 minute of birth and on the third,fifth,seventh day after birth.The 16SrDNA method was used to measure the intestinal flora,calculate the intestinal flora richness (the number of DGGE bands),Shannon-Wiener index and analyze the colonization of neonatal intestinal flora. Results: The number of DGGE bands within 10 minutes of birth was (4.18±1.69) and the Shannon-Wiener index was (0.92±0.26).The number of DGGE bands and Shannon-Wiener index within 10 minutes of birth were lower than those on the third day after birth.5 d,7 d and 3 d,5 d,7 d after birth,the number of DGGE bands and Shannon-Wiener index gradually increased (P<0.05 to P<0.01).The number of DGGE bands and Shannon-Wiener index of the intestinal flora within 10 minutes of birth,the 3rd and 5th days after birth,and the Shannon-Wiener index of newborns delivered by cesarean section were all lower than those in newborns delivered by cesarean section (P<0.05 to P<0.01).The number of DGGE bands and Shannon-Wiener index of the intestinal flora within 10 minutes of birth,the 3rd and 5th days after birth,and Shannon-Wiener index of full-term newborns were lower than those of preterm newborns (P<0.05 to P<0.01).The number of DGGE bands and Shannon-Wiener index of the intestinal flora on 3 d,5 d and 7 d were lower than those of non-exclusive breast milk newborns (P<0.05 to P<0.01). Conclusions: There are bacteria in the feces of newborns within 10 minutes of birth.Cesarean section,the feeding method and premature delivery will all affect the colonization of neonatal intestinal flora after birth.