Abstract: A method for the determination of gadolinium oxide and terbium oxide in cerium oxide by inductively coupled plasma mass spectrometry (ICP-MS) after separation with TODGA loading on diatomite column was established. The sample was dissolved by 50% (volume fraction) nitric acid solution and 30% hydrogen peroxide solution, and the sample solution containing 50 mg cerium oxide was introduced into the homemade TODGA loading on diatomite separation column, which was connected with a peristaltic pump to control the flow rate. The column was rinsed with pH 1.5 nitric acid solution at a flow rate of 2.0 mL·min^-1 until the mass concentration of cerium in the rinsing solution was less than 1 000 μg·L^-1. 60 mL of pH 0.92 hydrochloric acid solution was used to backwash gadolinium and terbium at a flow rate of 2.0 mL·min^-1, the first 20 mL backwashing solution was discarded, and the subsequent 40 mL backwashing solution was collected and its volume was made up to 50 mL with water. 10 μg·L^-1 cesium internal standard solution was added online, and the contents of analytes in the sample solution were determined by ICP-MS. The results showed that linearity relationships between mass concentrations of gadolinium oxide and terbium oxide and the intensity ratios of analytes to internal standard element were kept within 50.00 μg·L^-1, with detection limits (3s) of 0.102, 0.049 μg·g^-1. The proposed method was applied to the analysis of actual samples, giving determined values of gadolinium oxide and terbium oxide of 0.73, 0.68 μg·g^-1, RSDs (n=11) of the determined values were 4.8% and 5.2%, and values of recovery were 101% and 99.0%.