The effects of e xternal organic carbon addition and incubation temperature on soil organic carbon decomposition are the key factors to predict soil carbon dynamics under climate change in the future. We added 13C-labeled Chinese fir litter and glucose into soils from natural secondary forest and Chinese fir plantation fields, and incubated under four different temperatures to investigate the effect of external organic carbon addition on native soil organic carbon (SOC) decomposition. Our results showed that the native SOC decomposition was significantly stimulated due to Chinese fir litter and glucose addition. Glucose induced stronger priming effects than Chinese fir litter, and the priming effects in Chinese fir plantation soil were significant higher than in natural secondary forest soil. Moreover, the extent of priming effects consistently decreased with increasing incubation temperature; and external organic carbon addition significantly reduced the temperature sensitivity of the SOC decomposition. Our findings demonstrated that both external organic carbon and temperature play a vital role in SOC turnover in subtropical forest soil.