Castanopsis eyrei is one of the main dominant species in the mid-subtropical evergreen broad-leave forest, and plays an important role in the subtropical forest ecosystem in China. In order to reveal the differences in the vertical distribution of soil organic carbon content of Castanopsis eyrei natural forest at different altitudes and its influencing factors, this study took the single vegetation type of the natural forest of Castanopsis eyrei in Wuyishan Nature Reserve as the research object. Fixed sample plots were set up within the range of 5 altitude gradients (540 m, 700 m, 850 m, 1022 m, and 1200 m) distributed in a concentrated manner. By measuring soil factors (soil total nitrogen, total phosphorus, soil pH value, bulk density, soil organic matter, silt, sand and clay), climate factors (soil temperature), vegetation factors (fine root biomass) and soil organic carbon content at different depths of each elevation gradient, the distribution characteristics of soil organic carbon along the uplift and vertical soil layers were analyzed. A linear regression model based on principal component analysis was constructed. The results show that:(1) At the same altitude, the distribution of soil organic carbon content in the vertical profile of soil has obvious "surface aggregation" phenomenon; At the same soil depth, the content of soil organic carbon gradually increases with the increase of altitude, but the increase rate decreases with the increase of soil depth, and the high altitude area is conducive to the retention of soil organic carbon. (2) Soil organic carbon content in different soil layers is positively correlated with altitude, soil total nitrogen, soil water content and soil silt (P<0.01), and negatively correlated with soil temperature, soil bulk density, soil clay and sand (P<0.01);In the surface layer of soil (0-10 cm, 10-20 cm), the biomass of fine roots and soil organic carbon content, soil organic matter and soil organic carbon content are extremely significant (P<0.01) or significantly positively correlated (P<0.05). There is a significant negative correlation between soil pH and soil organic carbon content(P<0.05), and between soil sand and soil organic carbon content in 20-30 cm soil layer (P<0.05), but there is no significant correlation between these two factors and soil organic carbon content in other soil layers (P>0.05). Altitude is the main factor affecting the distribution of soil organic carbon content, followed by soil, and vegetation mainly affects the distribution of soil surface organic carbon content. (3) Altitude factors can affect the distribution of soil organic carbon by affecting the formation and transformation factors of soil organic carbon and changing the accumulation and decomposition rate of soil organic carbon. (4) The fitting R² of the multiple linear regression model is higher than that of the one-variable linear regression model, which can explain 82.1%-98.1% of the variation of soil organic carbon content. It can be seen that different combinations of environmental factors can better explain the variation of soil organic carbon content in different soil layers with altitude gradients.