Photosynthesis by terrestrial vegetation is the driving force for carbon (C) cycling between the Earth and the atmosphere. Information on the input and distribution of photosynthesized C in plant-soil systems is essential for understanding their nutrient and C dynamics. Stable isotope and labeling technology is one of the most effective methods to trace the C cycle processes in terrestrial ecosystems. In the present study, the ¹³C-CO₂ pulsing labeling method in combination with indoor incubation and the element analyzer-stable isotope analysis (Flash HT-IRMS) system were utilized to analyze the δ¹³C values of rice plants and soil. The distribution of photosynthetic C in different sections of the rice was compared and the photosynthetic C that was transferred to the soil C pool quantified. The results showed that the dry matter of the rice increased with growth stages, but the root-shoot ratio declined from approximately 0.4 at its highest during the tillering stage to approximately 0.2 at its lowest during the heading stage. The δ¹³C values of the rice shoot and root were between -25.52‰ - -28.33‰, which demonstrated an obvious fractionation pattern among different sections of the rice plant, and followed an order of stem (grain) > leaf > root. This fractionation pattern indicated that the distribution of photosynthetic C changes with progress of the rice growth stages. During early growth stages, the proportion of photosynthetic C distribution in the root and soil was high, implying a high C sink ability of the root-soil system; however, it decreased along with the growth stages of the rice, even though the total photosynthetic C accumulation in the root-soil system increased. As the results showed, during the tillering stage, nearly 30% of photosynthetic C was distributed to the underground parts of the plant for root formation and approximately 10% of this portion entered the soil organic C pool via root exudates. During the maturity stages, however, more photosynthetic C was distributed to the grain and the portion allocated to the soil decreased with growth of the rice. The present study provides scientific basis for better understanding the C cycle processes in paddy ecosystems. However, further study on the distribution of rice assimilated C in plant and soil systems, and the quantitative relationships of several C transformation steps such as input, transformation, protection, and stabilization in different ecosystems is required. The component and structure of new C input into the soil by rhizosphere deposition in C assimilation and its relationship with oxidation and mineralized stability should also be elucidated in the future.