Carbon(C) transport and C exchange between land atmosphere and land water body jointly determine the C balance of terrestrial ecosystem. However, due to the lack of effective observation data for a long time, inland water body on the Qinghai-Tibet Plateau (QTP) are unheeded C source or sink in the study of global C cycle. This study focus on the inland water body on the Qinghai-Tibet Plateau, to reexplore that the importance of C erosion and C deposition to the C sequestration potential of terrestrial ecosystem, systematically explained the C transportation and exchange processes between rivers, lakes, reservoirs, and the atmosphere and associated driving mechanism. The results showed that:(1) the part of rivers on the QTP had high weathering rates and CO₂ consumption rates, and strong erosion played an important regulatory role in the absorption and balance of CO₂ concentration by the Earth system; (2) the lakes on the QTP were an important carbon reservoir for inland ecosystems, and the carbon storage of lake sediments since 12 ka was about 73 kg C/m²; (3) the phytoplankton and aquatic plants in lakes on the QTP affected the deposition of C in inland water bodies, with an average annual primary productivity of (553 ± 36) mg C/(m²·d); (4) the lakes on the QTP were currently the “carbon source” with a carbon emission of approximately 2.27 Tg C/a. In addition, this study clarified the uncertainty estimation on the C source and sink process of the inland water, analyzed how to strengthen the C cycle research from a methodological perspective, and clarified the C source and sink mechanism of the QTP water body under global change, and looked forward to the research challenge on C source and sink function the inland water body on the QTP in the future. All these provide a scientific basis for in-depth understanding of the role of terrestrial ecosystems in the C neutralization process under global change.