The determination method of 12 major impurity elements in rodlike high-purity magnesium (including Al, Si, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sn, Pb and Bi) by glow discharge mass spectrometry (GD-MS) was established. The results showed that the discharge surface area of rodlike sample was small and the discharge was instable. When the discharge current was 47.0mA and the gas flow was 599mL/min, the matrix signal was stable. Meanwhile, the strength could meet the testing requirements. The pollution of Na, Fe and Ca on sample surface could be fully removed by pre-sputtering for 15min. The abundance of ²⁷Al, ²⁸Si, ⁵²Cr, ⁵⁵Mn, ⁵⁶Fe, ⁵⁸Ni, ⁶³Cu, ⁶⁴Zn, ²⁰⁸Pb and ²⁰⁹Bi was highest, and the analytical results were good under moderate resolution mode. Since ⁴⁰Ar had interference with the determination of ⁴⁰Ca, ⁴⁴Ca was selected as the determination isotope and the analytical results were good under moderate resolution mode. ¹²⁰Sn could be fully separated from ⁴⁰Ar⁴⁰Ar⁴⁰Ar when the resolution was higher than 7960, so ¹²⁰Sn was selected as isotope for determination under high resolution mode. Twelve impurity elements in rodlike high-purity magnesium were determined according to the experimental method. The relative standard deviations (RSD, n=5) were between 1.8% and 10.9%. The standard deviations (SD, n=5) of all analysis results were less than the repeatability limit specified in national standard method (GB/T 13748). The found results were compared with those obtained by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) with standard addition. The consistence of most elements was good. Since the relative sensitivity factor (RSF) of rodlike magnesium sample was different from the standard RSF, the determination results of Fe, Cu and Zn showed large difference. However, the determination results had no great influence on the purity grading of high-purity substance.