Iridium (Ir) coating was electrodeposited on tungsten (W) substrate for resistance to high-temperature oxidation. The reduction of iridium was studied using an electrochemical cyclic voltammetry (CV) measurement technique. The structure characterization and performance testing were carried out by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a high-temperature oxidation test. The results showed that the reduction of tetravalent iridium ions to metallic iridium included three reduction steps. The deposited iridium coating had a fine polycrystalline + amorphous structure, no grain orientation phenomenon was observed after electrodeposition, and the microstructure was isotropic. The iridium-coated tungsten metal had excellent resistance to high temperatures at 1300 K, which was attributed to the better chemical stability of the oxide film generated on the surface of the iridium coating.