Abstract: Internal standard method of ICP-AES has been adopted to determine Mo and Zr in Al-60Mo-20Zr alloy,dissolved in hydrochloric acid,nitric acid and hydrofluoric acid.The instrument working conditions are optimized,the spectral lines of Mo 202.030 nm and Zr 396.621 nm are selected as analytical lines and Co 231.160 nm internal standard line.Matrix matching method and internal standard method are used to eliminate the influences caused by matrix and instrument signal drift,improving the stability of determination of Mo and Zr.The results show that the standard addition recovery is between 98.3%—104.0% and that the relative standard deviation is less than or equal 0.78%,and that the linear correlation coefficient is above 0.999 8.The determination of Mo and Zr is in accordance with that obtained by X-ray fluorescence spectrometry,and under the same instrument condition,the proposed method is obviously better than external standard method in precision and accuracy.