Abstract: Objective: To analyse the differences of oral microbial diversity between healthy children and adults through high-throughput sequencing of 16S rRNA. Methods: Eleven specimens of saliva (5 from healthy adults, i.e. AJ group and 6 from healthy children, i.e. CJ group) were collected respectively. The DNA of microbes from saliva specimens was extracted, and the V4-V5 eras of 16S rRNA was sequenced by Illumina MiSeq sequencing platform. The diversity of microbial community structure from these two groups was analyzed. Results: The different genera between two groups were Leptotrichia, Porphyromona, Treponema, Gemella, and Granulicatella. Principal component analysis (PcoA) test showed that there were significant differences in microbial community structure between CJ group and AJ group. From 11 samples, 474,119 sequences and 9,223 operational takonomic units(OUTs)were obtained, which belonged to 26 phyla and 374 genera. Conclusion: The oral saliva microbial community structure in healthy adults and children is similar in kind but different in quantity. The differences suggest that healthy adults are more likely to get periodontal disease than healthy children while who are more likely to suffer from dental caries.