To retain the inner ambient temperature of the cryogenic wind tunnel, improve test efficiency and build large-scale cryogenic wind tunnel scientifically, this paper discusses the applicability of regular cryogenic insulation methods to cryogenic wind tunnel, summarizes the research status of the small-scale research-oriented cryogenic wind tunnel and analyses the differences among the external insulation, cold box, internal insulation and integration of internal and external insulation. Based on the literature analysis, it can be found that only the internal insulation is appropriate for large-scale production-based cryogenic wind tunnels. On this basis, three key technologies about the internal insulation system of large-scale cryogenic wind tunnel are elaborated, including designing, cryogenic fluid-structure-thermal analyzing and testing. Finally, future work on the design and construction of the internal insulation system of large-scale cryogenic wind tunnel are prospected.