Active soil organic carbon (ASOC) is an important component of soil. It plays a critical role in soil organic carbon turnover processes, which potentially contribute to future climate change. The properties of ASOC and its effects on methane (CH₄) emission from paddy soils remain unclear, and were therefore investigated in the present study. We determined ASOC, including microbial biomass carbon (MBC), dissolved organic carbon (DOC), readily oxidized organic carbon (ROC), and readily mineralizable carbon (RMC), for 3 consecutive years after application of organic fertilizer. The treatments used were as follows: (1) no fertilizer (NF); (2) chemical fertilizer (CF); (3) pig manure +chemical fertilizer (PM); (4) chicken manure + chemical fertilizer (CM); and (5) rice straw + chemical fertilizer (RS). The results demonstrated that (1): ASOC increased upon application of organic manures. The 3-year average content of ASOC in DOC, ROC, MBC, and RMC was 383.6, 2501.2, 640.4, and 291.7 mg/kg, respectively. The content of soil DOC, ROC, MBC, and RMC under different treatments was in the following order: RS>CM>PM>CF>NF. The content of DOC was 5.6%, 6.7%, and 19.3% higher in PM, CM, and RS, respectively, than in CF. The content of ROC increased by 6.6%, 8.4%, and 9.8% with PM, CM, and RS, respectively, over that in the CF treatment. The PM, CM, and RS treatments showed 5.1%, 14.8%, and 21.5% higher MBC contents and 6.8%, 22.0%, and 33.9% higher RMC contents, respectively, than CF treatment. The ASOC content was higher at the tillering stage than at the maturity stage. (2): The CH₄ emissions significantly increased with application of organic manure. The CH₄ emissions under different treatments were in the following order: RS > CM > PM > CF > NF. The CH₄ emission in PM, CM, and RS treatments increased by 37.0% (P < 0.05), 92.7% (P < 0.05), and 99.4% (P < 0.05), respectively, over those in the CF treatment. The CH₄ emission was 142-fold higher at the tillering stage than at the maturity stage. (3): With the increasing duration of application, CH₄ emission at rice tillering stage increased in different treatments. Positive correlations were observed among DOC, ROC, MBC, and RMC in all treatments. DOC, ROC, MBC, and RMC contents were strongly correlated with CH₄ emission, (e.g., the highest correlation coefficient between ROC and CH₄ emission, r=0.754, P < 0.05). The contents in DOC, ROC, MBC, and RMC at the tillering stage had a significant correlation with CH₄ emission, with correlation coefficients of 0.537(P < 0.01), 0.754(P < 0.01), 0.728(P < 0.01), and 0.431(P < 0.01), respectively. However, no significant correlation was observed at the maturity stage. In conclusion, ASOC content showed a close correlation with CH₄ emission, especially ROC and MBC content, which might be directly associated with CH₄ emission. The results of the present study suggest that, among the treatments tested, pig manure is the best organic fertilizer because the soil has lower ROC and MBC contents.Application of pig manure could be an effective measure to improve the quality of the soil, render it suitable for sustainable development, and mitigate CH₄ emissions.