Abstract: To investigate the seasonal dynamics of soil organic carbon (SOC) mineralization in Xiaoxing’an Mountain, we incubated soil samples collected from virgin Korean pine forest and broadleaved secondary forest in different seasons in the laboratory and measured the SOC mineralization rate and cumulative SOC mineralization (C_m). We employed simultaneous reaction model to describe C mineralization kinetics and estimated SOC mineralization parameters including soil easily mineralizable C (C₁), potentially mineralizable C (C₀). We also analyzed the relations between C_m, C₁ and their influencing factors. Results showed that the incubated SOC mineralization rate and C_m for 0-5 cm soil layer decreased from early spring to late autumn, while for 5-10 cm soil layer the seasonal variation was not statistically significant for both forest types. The C₁ in 0-5 and 5-10 cm soil layers varied from 42.92-92.18 and 19.23-32.95 mg·kg^-1, respectively, while the C₀ in 0-5 and 5-10 cm soil layers varied from 863.92-3957.15 and 434.15-865.79 mg·kg^-1, respectively. Both C₁ and C₀ decreased from early spring to late autumn. The proportions of C₀ in SOC for two forest types were 0.74%-2.78% and 1.11%-1.84% in 0-5 and 5-10 cm soil layers, respectively, and decreased from early spring to late autumn, indicating that SOC tended to become more stable as a whole from spring to autumn. The C_m and C₀ were significantly positively correlated to in situ soil water content and hot waterextractable carbohydrate content, but were not correlated to in situ soil temperature and cool waterextractable carbohydrate content. We concluded that soil labile organic carbon, soil physical and chemical properties contributed to the seasonal dynamics of SOC mineralization in the forests.