Abstract: In the determination of co-existing rare earth oxides as impurities in high-purity lanthanum oxide by ICP-AES as described in the GB/T standard 18115-2000,serious spectral interference by lanthanum was encountered and the use of monochromator of high resolution was required to solve this problem.It is reported in this paper that by the use of the axial-view whole-spectra ICP-AES equiped with echelle grating-CCD detector of the optimized selection of analyzing spectral lines,of the application of Fast Automated Curve-fitting Technique (FACT) for background correction,and the effect of acidity of analytes,satisfactory results of 14 rare earth impurities (as oxides) in high-purity La2O3 were obtained without using high-resolution monochromator,with their detection limits in the range of 3×10-4 to 0.022 mg·L-1 (3σ).