Abstract: The qualitative and quantitative inorganic anion analysis method by ion chromatography (IC) for MDEA solution was established. The multiple-step gradient model was affirmed being the best one to separate the inorganic ions in MDEA solution through comparison of different eluent patterns (such as degree model, step gradient model, multi-step gradient model). The quantitative external standard curves for analysis of F -, Cl -, Br -, NO3 -, SO4= anions in a mixed standard solution were established by multi-step gradient elution method, respectively. The linear correlation coefficients of above 5 inorganic anion concentration curves can reach more than 99% and the detection limit can be up to ≤10 g/L with high sensitivity. The results of repeatability and standard addition recovery tests show that the method has a high accuracy with the relative standard deviation less than 5% and the standard addition recovery rate between 95.9% ~105.6%. By the multi-step gradient elution method established, the concentrations of Cl -, NO3 -, SO4= inorganic anions in a MDEA solution used for a year or so are determined to be 1191.055, 3.155, 41.595 mg/L, respectively.