Abstract: In order to obtain the dynamic high-temperature properties of iridium alloy, the modified split Hopkinson tensile bar was used to conduct the tensile test under 103/s strain rate and temperature of room temperature, 600℃, 900℃ and 1100℃. Quick heating and precision controlling of the cold-contact-time were achieved by using high-current-heating method. It was found from the experimental resuts that with the temperature increases from room temperature to 900℃, tensile strength of iridium alloy decreases slightly and ductility increases slightly. Brittle fracture occurs for the iridium alloy. However, when the temperature increases to 1100℃, tensile strength of iridium alloy decreases substantially and ductility increases substantially. Furthermore, the iridium alloy demonstrates ductile fracture feature. Based on the macroscopical and microscopical characterization of the fractre morphologies, the deformation mechanism of iridium alloy is revealed. With the increasing temperature, the deformation mechanism of iridium alloy changes from predominantly intergranular fracture to predominantly plastic deformation and fracture of the granula.