Abstract: The etching of the plasma on the surface of tungsten under different etching conditions was studied,and analysis of its causes is helpful to further understanding the etching mechanism of tungsten in order to provide a certain theoretical support for how to improve the life of tungsten. By using Optical fiber spectrometer, the relative intensity of the excited tungsten atoms and tungsten ion spectra in the ECR plasma excited by different discharge conditions was directly reflected by the relative intensity of the spectra. The results show that the higher the bias voltage, the more severe the etching of the tungsten surface, and the pressure increased. The etching of tungsten increased with the increase of N₂ content in N₂-Ar mixture gas. While in contrast to the three types of gas of He, N₂, and Ar, the etching of He plasma was the most serious. Under the condition of 700 W and 0. 1 Pa, the etching of He plasma on the Rolling state tungsten was more serious than Re-crystalline tungsten in the range of 0-175 V, but the result was opposite after 175 V.