Infrared focal plane detectors are widely used in aviation, aerospace, military and other fields. It is urgent to develop large format, lightweight and high reliability infrared focal plane detectors and their dewar assembly in China. The selection of cold platform materials for infrared detector assemblies at home and abroad is analyzed, including Fe-Ni expansion alloy, low expansion alloys with high thermal conductivity, new ceramic materials, and so on. The source of thermal mismatch stress in infrared focal plane detectors and the solution to reduce thermal mismatch stress are summarized. Finally, some suggestions on the material selection of cold platform during the development of infrared detector are given, while involving the key technologies which should be studied under the development trend of infrared focal plane detectors assembly.