The creep behavior of Pt-5Ir and ZGSPt-5Ir high-temperature materials in the temperature range of 1423-1523 K were investigated. The results show that the creep property of ZGSPt-5Ir is better than that of Pt-5Ir because of ZrO2 addition. The creep characteristic of ZGSPt-5Ir is consistent with a structure-controlled creep process where some form of dislocation climb caused by lattice self-diffusion controls the creep deformation. And the fracture mode is brittle intergranular fracture. The creep characteristic of Pt-5Ir is consistent with mobility-controlled deformation where viscous glide of dislocations controls the creep. And the fracture mode of that is transgranular ductile fracture.