Abstract: 【Objective】 This study was performed to understand the effects of altitude on soil organic carbon chemical composition in a Pinus taiwanensis broad-leaved mixed forest and its preliminary influencing mechanism and changes in soil organic carbon stability in typical stands after global warming. 【Method】On the basis of the distribution range of Pinus taiwanensis on Fengyang Mountain, 1 200, 1 500, and 1 800 m were selected as the three altitudinal gradients, and three standard plots(20 m × 20 m)were set at each elevation gradient and sampled in August 2016. Solid-state nuclear magnetic resonance spectros copy was used to determine the chemical composition of soil organic carbon. 【Result】With an increase in elevation, the soil nutrient content increased and then decreased, and soil soluble carbon and phosphorus content at each elevation between significant difference(P < 0.05). With an increase in altitude, the N-alkyl carbon and alkyl carbon content initially increased and then decreased, and the aromatic carbon, phenolic carbon and carbonyl carbon content initially decreased and then increased. O-alkyl carbon and a cetal carbon content decreased with the increase in altitude at 1 200 m above sea level; at 1 200 m, the carbonyl carbon content was significantly different from those at the other two elevations(P<0.05). Non-metric multidimensional scaling ordination showed significant differences in soil organic carbon fractions at different elevations, mainly because of changes in carbonyl carbon, alkyl carbon, and Z_{alkyl carbon}/Z_{O-alkyl carbon}. Redundancy analysis showed that the soil total phosphorus content and soil bulk density have a great influence on the molecular structure complexity of organic carbon, soil total nitrogen content and organic carbon stability are significantly positively related. 【Conclusion】The physicochemical properties of altitude changes caused by the change of soil are important factors that affect the stability of soil organic carbon. Soil organic carbon has the lowest stability at 1 800 m, and low temperature can affect the decomposition of soil organic carbon, thus affecting the stability of soil organic carbon.