【Objective】Photosynthetic carbon (C), an important link of the carbon cycle in the atmosphere-plant-soil system, is closely related to the atmospheric environment and changes in soil quality, and plays a crucial role in the terrestrial ecosystem and global C cycling. Rice is one of the main grain crops in China, whose planting area is increasing year by year. Paddy soil is obviously quite high in C sequestration potential. Therefore, it is of vital significance to explore distribution of photosynthetic C in the paddy soil system and its variation to scientific evaluation of C cycling in paddy soil. 【Method】¹³C pulse-labeling and stable isotopic mass spectrometry technologies were employed to study variation of the assimilation rate and distribution ratio of photosynthetic C and their increasing rates in the rice-soil system relative to growth stage (regreening, tillering and heading stages) of the rice plants growing in a pot experiment. 【Result】The objectives of this study were toexplore turnover and distribution dynamics of photosynthetic C in therice-soil system at three different growth stages of the plants and to provide a theoretical basis for further researches on C cycling and renewal of soil organic C in the paddy ecosystem.Results show that photosynthetic C gradually decreased in total assimilation rate with the each passing day after ¹³C pulse-labeling (duration 5 h) of the rice-soil system conducted, separately, at the beginning of each growth stage. The total assimilation rate reached 75.92%~39.53%, 70.01%~52.02% and 86.38%~69.60% and the loss rate of assimilated photosynthetic C 47.93%, 25.70% and 19.43%, respectively, during the period from Day 2 after the labeling at the regreening, tillering and heading stageperiod. The assimilation rate of photosynthetic C was significantly higher in the heading stage than in the regreening and tillering stages, while an opposite trend was observed of the loss rate of photosynthetic C. The transformation of the photosynthetic C was offset between the above-ground and under-ground (including roots and soil) parts of rice in three growth stages. While the distribution ratio of photosynthetic C was much larger in the aboveground (mean 85.04%~73.10%) part than in the root (mean 12.50%~22.04%) and soil (mean 1.70% ~5.04%). The distribution ratio of photosynthetic C was higher aboveground, but lower underground at the heading stage than at the tillering and regreening stages.In addition, the increasing rate of photosynthetic C in soil during the three growth periods was 0.08% ~ 0.21%, 0.09%~0.17% and 0.19%~0.27%, respectively. The increasing rate of photosynthetic C in soil was higher during the heading period than during the regreening stage and tillering stage, and the photosynthetic C during the period was relatively stable in soil.【Conclusion】Under the experimental conditions, the assimilation and distribution of photosynthetic C in the rice-soil system varied with growth of the plants. The assimilation rate and distribution ratio of photosynthetic C aboveground was significantly higher at the heading stage than at the regreening and tillering stages, and the loss rate of photosynthetic C was significantly lower. The increasing rate of photosynthetic C in soil was higher at the heading stage than at the regreening stage and tillering stage, and the photosynthetic C at that stage was relatively stable in soil.