Effects of different utilization models of Chinese milkvetch and rice straw on characteristics of paddy soil organic carbon fractions under chemical fertilizer reduction were studied in order to provide a reference for rational utilization of organic materials for soil fertility control. A field experiments for five consecutive years (during 2011-2015) were designed to study the responses of the contents of purple soil total organic carbon (TOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), easily-oxidized organic carbon (EOC), and light fraction organic carbon (LFOC) to different utilization models of Chinese milkvetch and rice straw in double-rice cropping field of the Dongting Lake region in Nan Country of Hunan Province. The results indicated that F100 significantly increased the content of soil TOC, MBC, DOC, EOC, and LFOC, which was 12.2%, 19.5%, 18.5%, 11.3%, and 100.9% greater than that of the unfertilized control, respectively.?Compared with F100, different utilization models of Chinese milkvetch and rice straw could be more suitable for the accumulation of TOC, MBC, DOC, EOC, and LFOC under chemical fertilizer reduction. Wherein the optimal was F80+HR+A, which was 18.3%, 47.2%, 24.1%, 20.0%, and 204.0% greater than that of the unfertilized control, respectively. Applying Chinese milkvetch alone under chemical fertilizer reduction favored the buildup of MBC, DOC, and EOC, which was 9.8%, 4.0%, and 0.6% greater than that of rice straw alone, respectively, but the LFOC was the opposite, being 34.8% lower. Sensitive index showed that the LFOC and MBC had high activity, LFOC was more labile than MBC, and they could be used to evaluate soil quality. The sensitive indices of all organic carbon fractions in F80+HR+A were significantly higher than those of F100. Correlation analysis showed that there was a significant relationship among rice yield, TOC and its labile organic carbon fractions (p < 0.01). In conclusion, there were significant differences in TOC, labile organic carbon fractions among treatments amended with Chinese milkvetch and rice straw under chemical fertilizer reduction in purple soil. Returning?rice straw could be prone to increase TOC and LFOC pool, and application of Chinese milkvetch was favorable?to?promote MBC, DOC, and EOC. The pattern of Chinese milkvetch-rice straw synergistic dispatching, especially returning high pile of straw and winter?planting?Chinese?milkvetch,?could be prone to increase TOC and labile organic carbon fractions.