This paper summarized the characteristics of the temperature, salinity,surface CO₂ partial pressure (pCO₂) and sea-air CO₂ flux based on the in-situ CTD, CO₂ and others data in the South Yellow Sea during the winter of 2015. The results indicated that the west coast of the Yellow Sea was low temperature and low salt, affected by Yellow Sea Coastal Current. The central part of the southern Yellow Sea was high temperature and high salt, affected by the Yellow Sea Warm Current. In the coast, it was well mixed with generalized temperature and salinity in vertical. The average value of surface pCO₂ was (385.34±43.62)μatm. The distribution of surface pCO₂ had obvious regional differences. In the central sea, the pCO₂ was larger than that of the nearshore. Due to horizontal and vertical mixture of the Yangtze River water and the Yellow Sea Coastal Current, the northern part of the Changjiang River Estuary was atmospheric carbon sink where the maximum flux was 27.81 mmol/ (m²·d). However,overall regional average flux was (-2.47±3.91)mmol/ (m²·d) The higher pCO₂ in the southeastern of Shandong Peninsula controlled by the cold water, correlated to mixture of the high carbonate water brought by the Yellow Sea Coastal Current and the average flux was (0.11±0.80)mmol/ (m²·d). The winter mean flux in the Southern Yellow Sea was (-2.24±3.74)mmol/ (m²·d),which was carbon sink of the atmospheric CO₂.