Abstract: The spectral distribution of hollow cathode vacuum arc was acquired using spectrometer with different processing parameters, and the electronic excitation temperature of the arc plasma was calculated by the method of relative intensity. The results show that the hollow cathode vacuum arc plasma was composed of argon ions and argon atoms. The ion concentration in hollow cathode vacuum arc gradually increased with reducing the discharge pressure and increasing the welding current. At a certain gas flow,the electron excitation temperature in the hollow cathode vacuum arc gradually increased as the welding current increased. It is also found that the electron excited temperature was higher at lower gas flow and large welding current. If the discharge pressure became larger, the vacuum arc hollow cathode electron excitation temperature might decrease. With larger welding current and relatively lower gas flow rate, the argon ion spectrum intensity was high around the center axis of the hollow cathode arc. This was beneficial for welding with larger penetration.