This study proposed that the dissolution of calcium and magnesium minerals in river sediment could sequester CO2 and function as a carbon sink. Based on the published literature, the contents of CaO, MgO, calcite and dolomite in suspended sediment collected from 25 sampling points in the mainstream and 13 sampling points in the tributaries of the Yangtze River in 4 sampling campaigns during 2003~2007 were used to calculate the total inorganic carbon sink (TCS) capacity and nonsubstantial and substantial inorganic carbon sink (NSCS and SCS) capacities of suspended sediment along the river. Results showed that the TCS, NSCS and SCS caused by weathering of Ca and Mg minerals at Cuntan- Datong section were 2. 57×107 tons, 1. 70×107 tons and 0. 87×107 tons per year during the period of 1956~2000. Due to the reduction of sediment yield, the annual TCS, NSCS and SCS of the Cuntan- Datong section during 2006~2019 decreased by 18. 52×106 tons, 12. 24×106 tons and 8. 72×106 tons, respectively, compared to the period before 2002. The average annual sedimentation of the Three Gorges Reservoir (TGR) was 114. 5×106 tons, and the related TCS loss was 6. 76×106 tons, which were equivalent to 7. 9% of the 85. 8×106 tons of CO2 emissions reduced by the clean energy production of the Three Gorges Hydropower Station. The annual TCS of global rivers was estimated as 757×106 tons (the SCS was more than one quarter of the TCS), which is equivalent to 71.6% of the TCS by global rock weathering with 1.06×109 tons of sequestered CO2. The dissolution rate of calcium and magnesium minerals for offsite rock weathering was higher than that for in situ rock weathering.