Abstract: Based on the survey at the Yangtze Estuary and adjacent sea in March 2016, regional distributions of the surface water partial pressure of CO₂ and relevant parameters were analyzed, air-sea CO₂ fluxes were estimated and physical processes of CO₂ source/sink distribution were discussed.Results showed that the surface pCO₂ in survey area ranged from 321~575 μatm, generally exhibiting high values at the inner shelf, whereas low values off the shore.Until the end of winter, the distribution of surface pCO₂ had been dominated by the mixing between the estuarine water (low temperature, low salinity, high pCO₂) and the shelf water in the East China sea(high temperature, high salinity, low pCO₂), while vertical mixing had little effect on it.The Yangtze Estuary and adjacent sea also served as a weak sink of atmospheric CO₂, with a -4.43±7.41 mmol/m²/d average air-sea CO₂ flux.In the sight of regional carbon sink intensity, its level in the Changjiang Diluted Water was nearly in balance with that in the atmosphere.The Yellow Sea-East China Sea Mixing Water and Taiwan Warm Current Water were moderate/strong sink of the atmospheric CO₂, becoming a major contributor to the ocean absorbed CO₂ during winter.