A simple cathode sheath model has been used to discuss the influence of the electron emission on the properties of the cathode sheath (CS ). The model is applied to an argon arc plasma at atmospheric pressure with a thoriated tungsten cathode and the thermionic emission is mainly taken into account in this paper. However, the influence of the electric field intensity at the point of the cathode surface on the thermionic emission is also discussed briefly in this paper. The calculated results indicate that the electron emission has remarkably influence on the properties of the cathode sheath. A simple cathode sheath model has been used to discuss the influence of the electron emission on the properties of the cathode sheath (CS). The model is applied to an argon arc plasma at atmospheric pressure with a thoriated tungsten cathode and the thermionic emission is mainly taken into account in this paper. However, the influence of the electric field intensity at the point of the cathode surface on the thermionic emission is also discussed briefly in this paper. The calculated results indicate that the electron emission has remarkably influence on the properties of the cathode sheath.