Understanding the distribution and transfer of photosynthetic carbon (PC) in ecosystems is important to determine the fate of soil carbon (C). However, the allocation on plants of newly fixed PC during secondary succession is unknown. Using in-situ 13CO2 pulse labeling we report characteristics of PC turnover and driving factors that drive it in plants and soils at different successional stages on the Loess Plateau, China. Within 30 d of labeling, 13C abundance significantly decreased in plant leaves and stems, and significantly increased in roots, especially on farmland abandoned for 30a (from 114.67 mg·m−2 to 225.08 mg·m−2). The abundance of 13C in soils significantly increases over time, with 13C abundances in bulk soil 8a after abandonment being 8.17 % higher than those after 30a and 9.34 % after 15a. The contribution of newly fixed PC to soil organic carbon (SOC) was also significantly higher in soil 8a after abandonment than after 15a and 30a. Plant diversity and nutrients are the main factors to drive PC fixation and transfer. Because farmland abandoned for 8a has low plant diversity, high species evenness, and high plant nutrient contents, its plant-soil system fixes more PC. Plant diversity is a key predictor of PC fixation, and plant nutrients have an important influence on the transfer of PC. These results provide improve our understanding of vegetation restoration and terrestrial carbon sequestration in abandoned farmlands.