Comprehensive carbon chemistry (TA, DIC, pH, and fCO2) and other pertinent data (temperature, salinity, nitrate, and Chl a) were measured for the surface water samples collecting from the entire East China Sea (ECS) shelf in July 2007. Results showed that the spatial variations of carbon chemistry parameters were closely responded to the distribution of different water types. The lowest and highest TA values corresponded well to the least saline Changjiang Diluted Water (CDW) and the most saline Kuroshio Water (KW), respectively. The low DIC and fCO2 but high pH values of CDW and the Yellow Sea Water (YSW) were generally found in the northern part of shelf, while the high DIC and fCO2 but low pH values of the Coastal Upwelling Water (CUW) were observed in the southwestern shelf. Intermediate DIC, fCO2 and pH values of the warm and oligotrophic KW and Taiwan Current Warm Water (TCWW) occurred in the southeastern shelf. The CDW and the YSW were the two major CO2 sinks with fluxes of -7.2 to -12.5 and -5.9 to -11.4 mmolC m-2 day-1, respectively. The CUW was the most important CO2 source with a flux of 2.4 to 3.5 mmolC m-2 day-1. The KW and the TCWW were weak CO2 sources with fluxes of 0.7 to 1.2 and 0.4 to 0.6 mmolC m-2 day-1, respectively. As the while, entire ECS acted as a sink of atmospheric CO2 with a flux of -1.2 to -2.2 mmolC m-2 day-1 during the study period. On contrary to previous thought, result from this study, suggests that instead of high biological production, high TA input from Huanghe might contribute largely to the major sink in the YSW. Since the capacity of CO2 uptake is closely related to different water types, the change of circulation pattern in response to the reduction of CDW after the full operation of Three-Gorges Dam (TGD) may play an important role on the possible future change of the capacity of the overall ECS to uptake atmospheric CO2.