In this study， we investigated the abundance and diversity of lactic acid bacteria（LAB） and Bifidobacterium in 27 healthy young people from Hainan province using laboratory-designed LAB primers and Bifidobacterium-specific primers； this work also aimed to discuss the influence of sex， age， and body mass index （BMI） on the quantities of these two bacterial groups. The fecal LAB in the volunteers were mainly composed of Streptococcus， Lactobacillus， Weissella and Ruminococcus. According to the composition of LAB at species level， all volunteers could be divided into two enterotyping. The proportion of Streptococcus salivarius in the two enterotyping had significant difference（P<0.05）. The abundance and diversity of LAB in the gut of male volunteers were significantly higher than that in women. In addition， volunteers’ could be divided into three different groups according to the diversity characteristics of bifidobacteria. The representative bifidobacterial strains are B. catenulatum， B. longum and B. stercoris， respectively. Both gender and BMI are factors influencing the composition of bifidobacterial. This study has established accurate methods in determining LAB and bifidobacteria in human intestinal samples， as well as preliminary described the LAB and bifidobacteria subpopulations in subjects of Hainan province. Results obtained in this paper serve as good reference for other studies.