[Objective] The alpine wetlands in the Changjiang River source region are extremely sensitive to climate change. This study aims to investigate the distribution characteristics of dissolved carbon in these wetlands. [Methods] Water samples were collected from the river network, lakes, and thermokarst ponds within the alpine wetlands of the upper reaches of the Dangqu River in the southern Changjiang source region. Total dissolved carbon (TDC), dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) were measured in laboratory. Their concentration changes and relative proportions were analyzed. [Results] (1) Dissolved carbon in various water bodies within the upper Dangqu River wetlands predominantly consisted of DIC, and the mainstream exhibited the highest proportion of DIC, reaching 80%. TDC concentrations in water samples from the wetlands in the upper reaches of the Dangqu River ranged from 27.843 mg/L to 91.922 mg/L. The minimum value 27.843 mg/L was recorded in the Chadangqu tributary; the maximum value was measured at the eastern edge of the study area. TDC concentrations in thermokarst ponds were significantly higher than those in the mainstream and tributaries. TDC concentrations gradually increased from upstream to downstream. The six left-bank tributaries of the Dangqu River exhibited an average TDC concentration of 39.000 mg/L. The four right-bank tributaries showed an average TDC concentration of 45.506 mg/L. TDC levels in right-bank tributaries significantly exceeded those in left-bank tributaries. (2) The minimum DIC concentration in all water samples was 17.840 mg/L, and the maximum was 52.820 mg/L, with an average of 34.337 mg/L and a coefficient of variation of 0.291. DIC concentrations in water samples along the mainstream of Dangqu River increased progressively from upstream to downstream. DIC concentrations in wetland water samples from the upper reaches of the Dangqu River ranged from 17.840 mg/L to 52.820 mg/L. Among tributary water samples, DIC concentrations in upstream tributaries were generally higher than those in downstream tributaries. The mean DIC concentration for the six left-bank tributaries of the Dangqu River was 27.978 mg/L, while the four right-bank tributaries averaged 28.624 mg/L, indicating that right-bank tributaries generally exhibited slightly higher DIC concentrations than their left-bank counterparts. (3) To further elucidate variations in TDC across different regions of the Three Rivers Source Region, we also investigated the average dissolved carbon concentrations in representative rivers and lakes. The average TDC concentration in the wetlands of the upper reaches of the Dangqu River, the southern source of the Changjiang River, reached 49.055 mg/L, significantly higher than those in the Lancang River source (32.88 mg/L) and the Yellow River source (17.7 mg/L), as well as the average concentration in other alpine rivers in the Three Rivers Source Region (17.03 mg/L). [Conclusion] These findings provide valuable in situ data for studies on carbon cycling in alpine wetland waters in China and offer a key reference for climate change research in high-altitude regions.