Abstract: TiH alloy is a highly hydrogenated metal, which could be used as electrode of vacuum arc ion source and produces strong hydrogen ion current. TiH electrode surface has molten craters as the pure metal cathode does, and many pores form while hydrogen gas is released from the alloy. Hence TiH electrode surface has some special characteristics. This paper uses SEM to research the cathode surface appearances after single discharge and many times of discharges. The results are that the cathode spots are continuous distributions around the micro cracks, the gas pores make the surface look like cotton fiber, the numbers of cathode spots grow when the arc current grows, the spots move towards the place containing more hydrogen. These results are helpful to understand the progress of vacuum arc discharge with hydrogenated electrode, and to the applications of such morphology.