Abstract: Objective To develop a method for the determination of 16 rare earth elements in source water with inductively coupled plasma-mass spectrometry (ICP-MS).Methods The method for the determination of rare earth elements was established.Effect of acidity on response value was tested and the conditions of instrument operation were optimized with mixed tune solution.Indium was chosen as the internal standard,which was used to correct matrix interference and signal drift.Sixteen rare earth elements in source water were detected with ICP-MS.Results Under the optimized conditions,the linearity of the regression equations for the detections was good and the correlation coefficients of standard curves were all above 0.999 7 when the concentrations of 16 rare earth elements were within 0.0-100.0 μg/L.Detection linits of the method were within 0.004 μg/L-0.048 μg/L.Recoveries of the method were tested by adding standard solutions of the rare earth elements at high,moderate and low dosage.The average recoveries and the relative standard derivations of the method were within 90.0%-110.0% and 0.7%-4.8%.For the 10 source water samples measured,scandium (Sc) within the concerntration range of 1.48-4.33 μg/L,yttrium (Y) of 0.026-0.071 μg/L,and europium (Eu) of 0.012-0.042 μg/L were detected in all,5 and 6 samples.Conclusion The established method is of high sensitivity,good accuracy,low detection limit,and wide linear range and is suitable for the determination of rare earth elements in source water.