Abstract: Magnesite is an important industrial mineral raw material. The accurate determination of trace elements in magnesite is of great significance for the environmental protection, resource utilization, and geological research. Traditional analytical methods suffer from low sensitivity and inadequate capabilities in multi-element simultaneous detection, which cannot meet the efficient analysis requirements for trace elements. Therefore, an analysis method for the determination of eight trace elements（including As, Co, Cu, Pb, Th, La, U, and Li） in magnesite by inductively coupled plasma mass spectrometry（ICP-MS） was established in this study. The pretreatment conditions of sample were systematically optimized: the mixed acid system was composed of 5 mL HNO₃, 2 mL HF, 1.5 mL HClO₄ and 1.5 mL HCl; the sample was digested in closed system at 180 ℃ for 6 h; the sample mass was 0.100 0 g. The collision reaction cell technology was employed to eliminate the polyatomic ion interference caused by high-magnesium matrix. The mass spectrometry interference of As, La and U could be eliminated under kinetic discrimination（KED） mode（using He gas with 2% H₂）. The contents of Co, Cu, Th, and Li were determined under standard（STD） mode（He collision）. In addition, the mass numbers of elements for determination were optimized. ¹⁰³Rh was introduced online as an internal standard for the dynamic calibration, which effectively overcame the matrix effects and instrumental signal drift. The linear correlation coefficients of calibration curves for testing elements were all higher than 0.999. The limits of detection ranged from 0.001 to 0.008 μg/g, and the limits of quantification were between 0.004 and 0.025 μg/g. The contents of As, Co, Cu, Pb, Th, La, U and Li in CSMs magnesite composition analysis（GBW07865 and GBW07866） were determined according to the experimental method. The relative standard deviations（RSD, n=6） of determination results were between 2.6% and 3.4%, and the relative errors（|RE|） were between 1.75% and 4.88%. The analysis results of five actual magnesite samples indicated that the contents of eight trace elements were all at low level. Two samples of them were selected for the method comparison（this method and microwave digestion-ICP-MS）. The measurement results showed good consistency, which further proved the reliability of proposed method.