The invention relates to a device for testing electric arc in a high-speed electric sliding contact state. The device comprises a metal rotating disk, wherein at least one metal pin is arranged perpendicular to the rotating disk; the rotating disk, the metal pin and a testing power supply form a testing electric loop; and a part, corresponding to the rotating disk, of each metal pin is provided with a photosensitive element for detecting strength of the electric arc. In the device for testing the electric arc, linear sliding is converted into circumferential sliding, so that high-speed electric sliding contact and electric arc measurement can be conveniently performed; and the device has the advantages of simple structure of adopted equipment, low hardware requirement, easiness of implementation, accurate result and high reliability.