Abstract: The principle in acidimetric titration of mixture containing NaCO3 and NaHCO3 with double indicators was applied to the indirect determination of CO2-3 and HCO-3 in water solution by ICP-AES with gaseous sample introduction technique.A FI-manifold for generation of CO2 by reacting of sample solution with definite amount of dil.HCl solution,and introduction of the generated CO2 into the ICP-AES instrument by the carrier gas was designed and fabricated .The spectral line of 247.86 nm was chosen as analytical spectral line for measurement of emission intensity of carbon in CO2.Based on the calibration curve of concentration of carbon against the respective emission intensity,and on the curve of relationship between the concentration of carbon in CO2 generated from the sample solution and the different volumes of approx.0.01 mol·L-1 HCl added to react with the sample solution,contents of CO2-3 and HCO-3 in the sample were obtained by using the Excel software.Valus of detection limits (3s/b) found for CO2-3 and HCO-3 were 0.21 mg·L-1 and 0.82 mg·L-1 respectively.