[Objective] To reveal the effect of nitrogen（N）and phosphorus（P）additions on soil aggregate carbon in subtropical evergreen broad-leaved forests. Understanding these effects is crucial for comprehending the stability of soil organic carbon（SOC）and the carbon cycle within these ecosystems. [Methods] A series of N and P addition test platforms were established in an evergreen broad-leaved forest for a duration of six years，including control， 100 kg/（hm²·a）of N，50 kg/（hm²·a）of P，and a combination of 100 kg/（hm²·a）of N plus 50 kg/（hm²·a）of P. The response of soil organic carbon across different particle sizes to nitrogen deposition and phosphorus addition was assessed through particle size grading analysis，phosphorus component analysis，and evaluation of the molecular structures of organic carbon. [Results] The addition of nitrogen significantly increased the SOC mass fraction in macro-aggregates（>2 mm）as well as in clay and silt particles（<0.053 mm）. It also significantly reduced the degree of soil organic carbon decomposition（SD）in both macro-aggregates（>2 mm）and small aggregates（0.25~2 mm）. The combined application of nitrogen and phosphorus（N+P）led to a significant increase in the mass fraction of polysaccharides，alcohols，and phenols in macro-aggregates（>2 mm）. Additionally， it significantly decreased the SD in small aggregates（0.25~2 mm）and increased the mass fraction of resin（Resin-P） in labile phosphorus across various particle sizes，except in micro-aggregates（0.25~0.053 mm）. Redundancy analysis indicated that NaOHs-Pi and residual phosphorus were the principal drivers influencing the molecular structure of aggregates larger than and smaller than 2 mm， respectively. [Conclusion] Nitrogen deposition enhances the accumulation of recalcitrant phosphorus，thereby improving the chemical stability of soil organic carbon.