[Objective] To compare the differences in gut microbiota in 34-week-old infants under continuous breastfeeding with different delivery modes, and to explore the impact of delivery modes on the development of infant gut microbiota.[Methods] Healthy full-term breast-fed infants were recruited and 21 infants were still participating in follow-up at 34 weeks, including 16 infants delivered by cesarean and 5 vaginal delivered infants. The 16S rRNA of the gut microbiota was detected. [Results] The two groups of 21 samples contained 6 phyla: Actinobacteria, Bacteroides, Firmicutes, Fusobacteria, Proteobacteria and Verrucomicrobia; 57 genera were found. Among them, there are 26 genera in Firmicutes, 18 genera in Proteobacteria, 6 genera in Actinomycota, 5 genera in Bacteroides, 1 genera in Fusobacteria and 1 genera Verrucomicrobia. Among them, the content of Proteobacteria in the gut microbiota of the vaginal delivery group (44.17%) was higher than that in the cesarean section (16.10%); and the content of Actinomycetes in the gut microbiota of vaginal delivery infants (0.00%) was lower than cesarean delivery babies (0.09%). At the genus level, compared with the cesarean section group, the abundance of a total of 7 microorganisms in the vaginal delivery group was significantly reduced (P<0.05), namely Staphylococcus, Lactobacillus, Parabacteroides, Enterococcus, Haemophilus, Bifidobacterium and an OTU of Enterobacteriaceae. [Conclusion] The mode of delivery has an impact on gut microbiota of infants continued breastfeeding, and this impact still exists at 34 weeks after birth.