The challenges for infrared window materials are investigated in consideration of future hypersonic application. Some durable middle-wave infrared materials are compared in terms of high-temperature transmission range, infrared emittance, high-temperature mechanical properties, and thermal shock resistance. Yttria ceramics is considered as the best candidate for hypersonic application, and is possible to satisfy extending request such as multi-color or multi-mode integration, beyond visual range and wide viewing angle, and radar latent or anti electromagnetic disturbance.