Soil organic carbon (SOC) in farmland ecosystems is essential to agriculture and crucial to ecology and global climate change. Composition and mean residence time (MRT) of SOC are closely related to soil structural stability, sustainable soil nutrient supply, soil biodiversity and mitigation of greenhouse effect. Based on the three-pool first-order kinetics equation and the soil respiration incubation experiment conducted, the major organic carbon components of the paddy soil typical of Chengdu were measured for analogical analysis of SOC composition and for establishment of models for prediction of SOC components by means of quantification of soil properties as well as correlation and regression analyses of various fractions of organic carbon. Results show that the content of active carbon (C_a), slow carbon (C_s) and resistant carbon (C_r), was 0.42, 6.13 and 11.43g kg^-1, respectively, in the surface layer (020cm), and 0.23, 4.09 and 7.50 g kg^-1, in the sub-surface layer (2040cm). Obviously, the contents were higher in the surface layer than that in the sub-surface layer. Although the organic carbon in the sub-surface layer was higher than that in the surface layer in inertness, no significant difference was observed between the organic carbons in the two soil layers in proportion of components. No apparent difference was observed either between paddy soils derived from similar parent materials but sorted into different subgroups in content and proportion of organic carbon components. However, soil texture had some high impacts on content and proportion of organic carbon components in the sub-surface layer. In soil profiles (0100cm), contents of C_a and C_s decreased with increasing depth. However the decrease in content of C_r varied with soil subgroup, in some subgroups it decreased with soil depth, while in some it decreased first and then increased. In paddy soils the constituent proportions of C_a in all soil layers were less than 4% and no obvious change was found with soil depth; the constituent proportion of C_s was lower than that of C_r, and the two fractions of organic carbon varied with soil depth symmetrically, in constituent proportion, that is, C_s decreased with soil depth, while C_r increased significantly with soil depth. Paddy soils and forest soils shared some common characters in distribution of contents and constituent proportions of organic carbon components in soil profile, however, paddy soils, different in subgroup, had something common and something different, as well, in this aspect. Composition of soil organic carbon in paddy soils was subject to the integrated effect of bulk density, texture, particle-size composition,pH, carbon-nitrogen ratio, total nitrogen, total phosphorus, and total potassium, but each fraction of SOC had its own main affecting factors. The analysis results show that the contents of various organic carbon components were in extremely significant negative relationships with bulk density, and in extremely significant positive relationships with total nitrogen and total phosphorus. Clay was favorable to preservation of C_a, and weak alkaline environment was conducive to soil carbon sequestration. Based the relationships of the fractions of organic carbon with various related factors, the significant linear relations (R²= 0.69) observed of C_a with total nitrogen and pH and the significant linear relations of (R²= 0.70)C_r with soil total nitrogen, carbon-nitrogen ratio, pH value as well as the content of fine silt (0.020.002mm), it is feasible to predict contents of various fractions of organic carbon in paddy soil, but the prediction accuracy needs to be improved. However, the findings of this study has some positive reference value to researches and prediction of components of SOC in other regions.