The concentrations of major ions in the Longcanggou streams were determined in order to analyze the relative contributions of chemical weathering of different sources and to estimate the chemical weathering rates of different rock types and associated atmospheric CO2 consumption rates. The streams pH are close to neutral, with an average pH of 6.82. Calcium ion accounts for 56% of total cations, and HCO3- for 45% of the total anions. The dissolved cations are originated from carbonate weathering（50.2%）, silicate weathering（38.2%）, atmospheric input（10.5%）, and anthropogenic pollution（1.1%）. The average chemical weathering rate of silicates of the Longcanggou catchment is 37.54±24.94 t/km2/yr, and the associated atmospheric CO2 consumption rate is 5.4±3.6 mol C/km2/yr. For the whole Emeishan basalt area, we firstly estimated the total annual atmospheric CO2 consumption flux of the Emeishan basalt is 1.35±0.89×1011 mol C/yr, which accounts for 3.31±2.18% of the annual CO2 consumption flux by global basalt weathering.