The even and compact Ir coating was deposited on Ta-10W alloy substrate by arc ion plating.The oxidation resistance and thermal shock resistance of Ir coating at high temperture was studied.Results show that the Ir coating can keep protecting Ta-10W alloy substrateat at 800℃ and 1 100℃.The light oxidation occurs and bowrn oxides appear on surface after 20 h.At 1 900℃, the oxidation resistance of life reachs 10 hours and above.Under temperature change from room temperature to(1 900±50)℃, the times of the thermal shock is 1 000 over cycles.