The cathode surface temperature is an important parameter in the vacuum arc plasma discharge process, which has an important influence on the formation of vacuum arc plasma, electrode corrosion prediction, heat conduction and ion source lifetime. The cathode of the vacuum arc ion source has the characteristics of the small target and fast discharge process, and its temperature measurement requires high time resolution and spatial resolution. The lack of measurement techniques for the surface temperature of the cathode makes it difficult to verify the results obtained by theoretical analysis alone. Moreover, the measuring instrument is highly susceptible to arcing during plasma discharge. How to avoid plasma radiation during discharge is also a problem to be considered when measuring the surface temperature of the cathode by radiation. This undoubtedly brings difficulties to the testing of its temperature field. It is important to carry out the cathode surface temperature test experiment for pulsed vacuum arc plasma. In this paper, the vacuum arc plasma discharge characteristics and background radiation characteristics and the practical requirements of plasma discharge cathode temperature measurement are analyzed. A novel multi-spectral pyrometer is developed based on the high-speed CCD camera. In order to realize multi-spectral radiation temperature measurement using a monochrome CCD camera, an optical system of a pyrometer is designed, and the optical system adopts a 4-aperture spectroscopic system. For the first time, four different wavelength filters are embedded in one filter. The pyrometer designed in this paper can be used for plasma temperature measurement from 2 000 to 6 000 K. The field test was carried out at the Institute of Electronic Engineering of China Institute of Physics and Engineering. The pyrometer to be developed during the test was tracked and shot by the external trigger form. The pyrometer completely captured the plasma discharge process. The pyrometer was verified by the measured data of the vacuum arc plasma metal electrode cathode discharge. The experimental results show that the designed multi-spectral pyrometer can be used to measure the cathode temperature field information during vacuum arc plasma discharge. The measured temperature value is lower than the boiling point temperature of the discharge electrode, which is consistent with the gasification phenomenon during plasma discharge. It is stated that the pyrometer measures the temperature of the plasma discharge cathode.