Abstract: An inductively coupled plasma mass spectrometric method after matrix separation was developed for the determination of 13 impurity elements in high purity selenium. Selenium was separated under low sublimation temperature and vacuum conditions. An appropriate internal standard element was chosen and the influence of matrix effect was investigated. The results showed that caesium was the appropriate internal standard element for the elements to be measured, with residual selenium under 100 μg/mL, and do without interference for the determination of impurity elements. The limit of determination was 0.007~0.033 μg/g, the relative standard deviation was 5.7%~19% and the spiked recovery was 90%~115%. This method can be used to determine trace elements in high purity selenium of 99.999 9%.