Abstract: The disk electrode of a gas switch with different materials is studied by self-breakdown experiment in slightly uneven electric field. In the self-breakdown experiment, the gap length and the gas pressure of the switches are identical .The gap length is 5 mm and the gas pressure is 0.25 MPa, so the self-breakdown voltage of each switch is almost 40 kV. Stainless steel, brass, tungsten-copper alloy and graphite are studied in the experiment. The differences of switch performance, like static performance, electrode mass loss and electrode surface, are compared in the research. The experiment result shows that the probability of self-breakdown at low working ratio of the graphite electrode switch is much lower than the others of metal material electrode switches. There is little difference of the static performances among the metal electrode switches. Mass loss of graphite electrode is higher than that of other electrodes. But, because most of the graphite ablation production is gas, the insulator of the graphite electrode switch is polluted much more lightly than that of others.The ablation of the tungsten-copper alloy electrode is lighter than that of others.