[Objective] To understand the diversity characteristics and possible causes of gut bacterial composition of healthy Tibetan and Han population in the same age group living in the same environment. [Methods] Healthy male students including 20 Tibetan and 20 Han aged 20-24 in the same major of the same campus volunteered for this study. Total DNA was extracted from fresh feces collected at the same day from male healthy Tibetan and Han students in the same grade. The V3-V4 region of 16S rRNA were amplified by PCR then sequenced on Illumina MiSeq platform. The sequencing results were analyzed with bioinformatic softwares combined with Dietary status questionnaire to study the relationship between gut bacterial diversity and dietary habits of healthy Tibetan and Han students. [Results] A total of 2880 OTUs were obtained from 40 samples. Alpha and beta diversity analysis showed that male students from different ethnic groups had significantly different gut bacterial compositions under the same environment. Prevotella 9, Bacteroides, Lachnoclostridium and other 15 genera are shared by both Tibetan and Han students. Meanwhile, the composition and abundance of 10 genera, such as Prevotella 9, Faecalibacterium, Succinivibrio etc., are the biomarkers that have significant influence on the difference of intestinal bacteria composition between the two ethnic students. Further cluster analysis showed that all the student samples were divided into three enterotypes:ET F, ET P, mixed ET F and ET B. The follow-up survey results showed that different enterotypes corresponded to different dietary habits based on fat and starch. [Conclusion] Living in the same environment, the composition and differences of gut bacteria of healthy Tibetan and Han students may be closely related to genetic factors and dietary habits.