Mangrove ecosystems in tidal flats usually contain a large proportion of soil nutrients, especially organic carbon content in sediments. The basic research on organic carbon components of the sediments in the large variety of luxuriant mangrove forests in Hainan Island can help more accurately evaluate the carbon sequestration capacity of mangrove wetlands and improve the knowledge about marine blue carbon. This paper comparatively analyzes the different contents of total organic carbon (TOC), microbial biomass carbon (MBC), easily oxidized organic carbon (EOC), and dissolved organic carbon (DOC) in the topsoil (0-10 cm) in five typical populations of mangrove in Qinglan Port and their correlation with soil factors. The result shows that (1) the average contents of TOC, MBC, DOC and EOC in the surface soils in different populations of mangrove are 66.76 g/kg, 177.08 mg/kg, 25.49 mg/kg, and 2.34 g/kg, respectively. According to the comparative analysis, the content of TOC is the highest in the soil in the Ceriops tagal community, but it is not significantly different among all the communities;The content of MBC in the soil is significantly different among all flora communities, where the content of MBC in the soil in Ceriops tagal community and Sonneratia alba community is much higher than that in Lumnitzera racemosa community. The content of DOC in the soil in all communities is significantly different, where the content of DOC in the soil in Bruguiera sexangula community and Ceriops tagal community is much higher than that in other communities. The content of EOC in the soil in all communities is significantly different, where the content of EOC in the soil in Ceriops tagal community is much higher than that in Bruguiera sexangula community and Rhizophora Apiculata community. (2) The average ratio of active organic carbon components to total organic carbon in MBC is higher than in DOC, and that in EOC is the highest. The distribution ratios of EOC, MBC and DOC in soil are between 3.23% and 4.02%, 0.22% and 0.36%, and 0.02% and 0.08% respectively. (3) Redundancy analysis shows that total nitrogen (TN) in soil is more justified to exclusively prove organic carbon components in the soil. Soil pH is less justified to exclusively prove the organic carbon component in the soil. (4) TOC, MBC, DOC and EOC in soil are positively correlated with soil TN and soil water content (SWC). In conclusion, tidal level soil physical and chemical properties caused by different biotic communities jointly affect the concentration of soil active organic carbon components.