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.