Abstract: Based on the strict quality requirements of the metal ion content in high purity magnesium based oxides, through the discussion of plasma parameters, spectral parameters, analytical spectral lines, types and acidity of dissolved sample medium, interference of coexisting elements and other factors, a method for determination of 10 trace elements (including Ca, K, Na, B, Fe, Mn, Cd, Pb, S, and Al) in magnesium oxide and magnesium hydroxide was developed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Under the optimal conditions, detection limits (3s) of 10 elements were found in the range of 0.000 9-0.029 1 mg·L^-1, and lower limits of determination (10s) of 10 elements were found in the range of 0.003 0-0.097 1 mg·L^-1. Values of recovery was kept in the range of 97.6%-101%, with RSDs (n=11) of the determined values in the range of 4.5%-20%.