Soil organic carbon (SOC) is one of the most important pools in forest ecosystems. The labile fractions of the SOC pool play critical roles in the SOC turnover processes and are a sensitivity indicator of SOC responses to future climate change. In this study, nine typical forest ecosystems (Jiangfengling, Dinghushan, Jiulianshan, Shengnongjia, Taiyueshan, Donglingshan, Changbaishan, Liangshui, and Huzhong) were selected along the North-South Transect of Eastern China (NSTEC), and covered tropical, subtropical, and temperate climate zones. The SOC, easy-oxidized organic carbon (EOC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC) contents were measured in the 0-10cm soil layer, and climate factors, soil texture, soil microbes, and vegetation biomass were used to explore the latitudinal pattern of SOC fractions in forests and the main factors influencing them. The results showed that the SOC, EOC, MBC, and DOC contents were 23.12-77.00 g/kg, 4.62-17.24 g/kg, 41.92-329.39 mg/kg, and 212.63-453.43 mg/kg, respectively. SOC, EOC, and MBC increased exponentially as the latitude increased (P < 0.05), whereas DOC decreased exponentially as the latitude increased (P < 0.05). The SOC and EOC contents in forest soils were in the following order: tropical forest < subtropical forest < temperate forest (P < 0.05), and the order for DOC content was tropical forest > subtropical forest > temperate forest (P < 0.001). The results of the structural equation modeling showed that climate, soil texture, soil microbe, and vegetation biomass significantly affected the spatial variations in SOC fractions, and they can explain 74%, 65%, 51%, and 76% of the variation in SOC, ECO, MBC, and DOC, respectively. Furthermore, the latitudinal patterns for the SOC fractions were mainly controlled by climate, with soil texture as the sub-dominant factor for SOC and EOC, and soil microbe and vegetation biomass as the sub-dominant factors for MBC and DOC, respectively.