For understanding the law on the atmospherical CO₂ consumption effect due to Dissolved Inorganic Carbon (DIC) discharged from the chemical weathering processes in the Source Drainage Basins Area of the Karst region, a riverine hydro-chemical investigation is carried out during the entire hydrologic year from June 2010 to May 2011 in the water channel of the Xiangyang Hydrological Stations located at the Bainihe watershed in Wujiang River Source Drainage Basins Area, that the cover layer is mainly carbonate as well as Karst landforms are widely developed. The variation of the Total Dissolved Substances (TDS), its sink flux to atmospherical carbon, and intensity change in the cross-section studied are analyzed. Result indicates that the annual fluxes on the TDS are amount of 6.37×10¹⁰g with 7.495×10⁷g·km^-2·a^-1 in chemical weathering modulus, and the annual fluxes of the DIC are amount of 5.483×10⁸mol with 6.45×10⁵mol·km^-2·a^-1 in DIC weathering modulus. Based on the carbonate weathering contribution rate amounting to 98% of the riverine DIC, the annual fluxes of the atmospherical CO₂ consumption at Xiangyang Hydrological Stations of the Bainihe watershed are about 2.819×10⁸mol with 3.32×10⁵mol·km^-2·a^-1in modulus, about 95% of which are discharged during the hot-rainy period from June to November in the year surveyed. Impacted strongly by Karst process, the chemical weathering and its carbon consumption are closely related to the characteristics of watershed land surface, climatic condition, as well as hydrological processes in the Bainihe watershed.